When you buy a retail copy of Windows Vista, the most important part of your purchase is the product key that comes with it. That 25-character key determines which Vista edition you're allowed to install and activate, and it also tells the Setup program whether you've purchased a full or upgrade license. (That detail is important, as I'll explain tomorrow.)

Vista keeps track of licensing details using a service called Software Licensing. Slmgr.vbs, a VBScript file included with all Vista editions, allows you to query the current installation and see details about your installation and your licensing status

Thanks to the radically revised Setup program in Windows Vista, Windows users can safely discard one of the basic tenets that have governed installation decisions since the beginning of the Windows era.

That's right - you can now safely point Windows Setup to a partition on which Windows is already installed, as long as you have at least 15 GB of free disk space and you don't plan to use the copy of Windows on that partition anymore. When you choose to do a clean install in this configuration, Windows Vista Setup moves the old Windows, Program Files, and Documents and Settings folders to a folder named Windows.old. Your new installation creates a brand-new set of top-level folders on the current system drive: Windows (for system files), Program Files (for application files), and Users (for data associated with each user account on the system).

Any day now, the folks who bought new PCs that qualified for free Windows Vista upgrades through Microsoft's Express Upgrade program will begin receiving their disks. Others are buying shrink-wrapped retail upgrades. For most people, the upgrade process should be straightforward. But a relatively small handful of people will be stymied during the upgrade process by two disk-related gotchas:

• Free disk space
• Disk format

Anyone who wants to run multiple versions of Windows (and other operating systems) on a single PC needs to learn about the changes in Windows Vista's boot process. Carl Siechert, Craig Stinson, and I explain the process in detail in Chapter 2 of Windows Vista Inside Out; here's the short version.

Metadata within a file can tell a lot about you. Cameras record data about when a picture was taken and what camera was used. Documents and spreadsheets contain details about their creators. Music files are tagged with artist and album information. With user-created tags, you can add personal and business details that might be useful on a local copy but are unwise to disclose in the wider world.

Windows Vista introduces a fundamental change in the way user data is stored. The XP-style Documents And Settings folder is gone, replaced by the Users folder, which is located in the root of the system drive. Each user account has its own profile folder here, which contains 11 folders, each devoted to a different type of data.

Although you can partition a single drive into multiple volumes, I recommend using two separate physical drives for maximum data security; in a two-drive configuration a hardware failure doesn’t wipe out everything.

Moving your user data folders is ridiculously easy.

Microsoft doesn't get enough credit for one major change in Windows Vista. Using the standard Setup program and installation media, you can install an evaluation copy of any Vista edition and use it for a minimum of 30 days, with the option to "rearm" that trial period up to three times, for a total evaluation period of 120 days.

In essence, this makes Windows Vista the ultimate shareware program. You don't need to enter a product key, and you can beg, borrow, or copy the media. When you're done, you'll have a fully functioning evaluation copy that is not limited or crippled in any way during the trial period.

As I pointed out in yesterday's Vista Hands On installment, you can install an evaluation copy of any Vista edition and use it for a minimum of 30 days without having to activate it. As several publications have already noted, you can renew this evaluation period a total of three times, extending the evaluation period to roughly 120 days. But this post contains a secret technique that no one has yet published: how to automatically "rearm" the trial period at the end of each 30 day period.

The not-so-secret technique is simple: Open an elevated Command Prompt window (type cmd in the Search box, right-click the shortcut, and choose Run As Administrator from the shortcut menu). At the prompt, type slmgr.vbs -rearm and press Enter. Restart your computer. Done.

I’m traveling this week with a year-old Tablet PC running a fresh copy of Windows Vista Business, so it’s a good time to focus on some of Vista’s mobility features. The hotel where I’m staying offers free wireless access, so it’s given me a chance to rediscover Vista’s tools for managing wireless connections.

As with anything network-related, the starting point is the Network and Sharing Center

In Vista Hands On #7: Move user data to another drive, I recommended using two separate physical drives for maximum data security. In that configuration, if your primary drive fails it doesn’t wipe out everything."

But what if you have only a single drive? Then use the next best option and set up dual volumes (that's Windows' preferred term for what you probably think of as partitions). Use one volume for system and program files and use the other for data.

The good news is that you can easily set up this configuration using partition-management tools that are new in Vista. For the basic task of splitting a disk in two and adjusting the relative sizes of volumes, you don't need third-party software.

Earlier this week I explained how to create separate system and data volumes when setting up Windows Vista from scratch. Today, I'll explain how to accomplish the same goal on a system where Windows Vista is already set up. In previous Windows versions, this task required either third-party software or a full backup, followed by a format and restore. In Vista, the capability to shrink and extend partitions is built into the Disk Management console.

For this scenario, I’m going to assume you’re working with a new system that arrived with Windows Vista preinstalled on a single disk with a single partition – in this example, a 160GB SATA drive. The goal is to take that 160GB and shrink the system partition to 60GB, leaving the remainder for storage of data files

When a Windows tip becomes popular, it spreads through the community like wildfire. Unfortunately, there’s usually only a random relationship between the speed of transmission, the quality of the advice, and its relevance to you.

Case in point: I’ve seen at least 10 sites this week echo a tip that shows how to use an obscure command-line tool to trim the amount of disk space Windows Vista sets aside for System Restore. But is this good advice? Before you start chopping, make sure you understand the facts and the alternatives.

When people complain about the redesigned user interface in Windows Vista, the poster child for the “it’s too complicated” crowd is the Network and Sharing Center. And when you probe for more specifics, the complaint usually boils down to this, as expressed by Jason Hiner at TechRepublic: For Microsoft’s UI designers, this seems like a can’t-win design decision. Most people set up a network connection once and then rarely need to tweak its properties again. But corporate users who lug portable PCs between home and office might need to tweak settings more often. If you want easy access to the properties for a specific network connection, it’s easy to set up an efficient alternative interface.