After the whole Vista fiasco, I too was VERY hesitant to move to Windows 7. I absolutely HATE Vista!!!! I was forced to buy it when I had to replace a laptop the same month it was released and P__ Off that Microsoft wouldn't allow retailers to sell computers with XP anymore. I clearly remember all the Mac commercials making fun of Vista!! They were all SO true!!!! I hated Vista so much that I downgraded it to XP. When I bought my current desktop, I had to buy it online in order to get one that would run XP.
I'd never heard anything bad about Windows 7. I asked around about it and everyone told me that they were very pleased with it. I made the decision to upgrade knowing I could always put XP back on my computer if I didn't like Windows 7. The fact that I was eligible to buy Windows 7 for $15 dollars at the university I'm attending was also a big incentive!!
I have never regretted it. It is much, MUCH faster than XP and it doesn't get hung up like Vista often does. Some of the old XP programs aren't compatible with 7, but you can download XP mode, a virtual computer, from Microsoft that you can run straight from the Win 7 desktop.
If you do this, make sure you have virus protection installed as a separate instance on the virtual machine as well! Or, disable access to the internet by the virtual machine. Using the virtual machine is like having a completely separate computer. It is NOT protected by the virus protection installed in Windows 7.
Make sure your system is compatible with Windows 7 by downloading the Upgrade Adviser.
Upgrading from XP requires a custom installation. It's really not difficult. Follow this link for for a video that will walk you through it.