Check Your Machine's Specs
The first thing to do is check whether your desktop or laptop PC is capable of running Windows 7. If it's already running Vistawith acceptable performance, then the answer is yes. Officially, you need at least a 1-GHz CPU and 1GB RAM, but testers of the OS have successfully got it running on machines as out of date as a 266-MHz Pentium II with 96MB of RAM. Go ahead and try that kind of thing if you want, just don't use your license key on that type of machine. It may run, but you'll spend a lot of time waiting for it, and it won't display the glassy new Aero interface and enhancements.
If you're unsure whether your current system can run Windows 7, download and run Microsoft's Upgrade Advisor to assess your hardware's capabilities. When I ran it on an aging XP laptop, it told me I needed to back up my files and perform a Custom installation (see below), that my hard disk didn't have enough free space (you need 16GB), and that the laptop wouldn't run Aero Desktop. The good news, however, was that my 1.6-GHz CPU and 1.5GB RAM were sufficient. The advisor actually checks a lot more than the basic system requirements, and it lists every piece of hardware and software you have installed at the bottom of its report.
Choose an Edition
Home Premium, Home Basic, Professional, and Ultimate.The key thing to consider here is that you have to do a clean installation without the ability to carry your apps along if you move from one level of Vista to another level of Windows 7, say from Vista Home Premium to Windows 7 Professional. The exception is Windows 7 Ultimate, which will let you perform an in-place upgrade from any level of Vista as long as you don't change whether you're using the 32- or 64-bit version.
After that Choose 64-bit or 32-bit
After Running Setup
Once the setup has run its course, you'll be asked to type in a username (20 characters maximum) and computer name (15 characters maximum). Then you're asked for a password, password confirmation, and password hint. (You can bypass this last step if you're not worried about others getting into your PC.) After this, you're supposed to enter your product key, but since you have a 30-day trial, you don't need to right away. The same page by default sets the system to automatically activate Windows, but you may want to uncheck this if you're just trying out the OS. After 30 days, you'll see messages and warnings that you need to Activate, so it's not like you can forget about it.
Then you choose Security settings. The large choice at the top for Default Settings makes a lot of sense—it turns on automatic updates and checks online to resolve problems. The other two choices, "Install important updates only" and "Ask me later," leave you a bit less protected. After this, you'll be prompted for your Time Zone and be given a chance to check the date and time. Windows gets this over the Internet, so you shouldn't have to set it manually.
Now comes the Welcome screen and the "Windows is preparing your Desktop" Message. And that's it—you're running Windows 7! You'll likely see updates in available in Windows Update, which will probably require a restart.