It looks like many people have problems updating from Vista to Windows 7.
Some people who tried to upgrade even encountered some serious reboot loops (caused by a broken update installation).
I always recommend a fresh and clean install to my friends, because that is simply the best way, although it involves more work.
Luckily, Microsoft is acting fast and updated the “Windows 7 Upgrade Advisor” for Windows XP/Windows Vista. This tool checks if your system is ready for Windows 7.
Download Windows 7 Upgrade Advisor
You can download the upgrade advisor from Microsoft.com: Download Upgrade Advisor (XP/Vista)
The Upgrade Advisor scans your hardware to see if it can run Windows 7 without problems. This can come in handy, but use it with caution! This tool might come up with some false positives.
Windows Compatibility Center
Then there’s the so called Windows 7 Compatibility Center:
This website allows you to check software and hardware to see if it’s compatible with Windows 7. The database includes thousands of entries, you can even select a system type and check for x64 entries only. Aside from that you will find plenty of links to drivers and software for your hardware.