I have installed and activated Win 7 on my desktop. The installation went super smooth. I deleted my old XP SP2 partition and started a fresh install. You have the option of it making the "old.windows" folder for your OS, but I didn't really need it. After that the installation went super smooth, 30 minutes later it was up and running.Also, I did not have to install ANY drivers which was really nice.
The activation took a bit longer. I have a Asus mobo and it was being finicky. Non of the options the loader was giving were working "none slic option1", "non slic option 2", and "slic present". I ended up modding the newest version of my bios and adding the SLIC 2.1 for Dell into my mobo so that it would activate. I could not find the Asus Slic 2.1. Once, I upgraded tho the activation worked straight away and its all good.
Windows 7 is a pretty nice piece of software. The jump from XP to 7 is pretty nice. The only issue is getting used to it, which took no time at all. When you hear someone say "it is what Vista should have been" they were right. I did have one issue, my 500gig SATA hdd wasn't being recognized. This was easily fixed, I guess it was not given a drive letter thats all.
Here is the Asus bios fix guide: http://forums.mydigitallife.info/showthread.php?t=6921
I am not that much of a computer guy, so if I said anything weird sorry.