As far as I know, nothing really secret to it.. There's a system advisor tool from microsoft, might help find potential issues that could prevent your system from running windows 7.

I think it has drivers built in for much of the recent hardware. If you have a quad core 64 bit processor, and lots of ram, you'd want to get the ultimate/64 bit version.

There's some mention of UAC issues in the beta releases that was supposed to be fixed on the retail release. Alot of the discussions about 7 went on durring the beta release, might want to search a few of the more active tech sites for complaints about hardware/software issues.