I'm using Windows 7 here, and one of the first things I did after getting my video driver installed was install FSO again.
One word: Orgasmic.
1. FSO plays better on Windows 7 for some reason, even though Windows 7 is using more of my CPU and RAM at a time. Windows XP had lag on high detail, causing me to set it to Medium. FSO on Windows 7 has little-to-no lag on high detail.
2. Somehow, when I updated to Win7, I managed to squeeze better quality sound out of my soundcard and speakers, even though I'm using the same drivers. I can finally hear how much better the HQ music in the MediaVPs is!
3. Cutscenes and missions load faster.
Among other things, I'd say I'm rather impressed.
Long live the emperor FSO!