hi guys,im new to this website...just spotted this forum,thought i might be able to help
(doubt it but ill try lol)
Long story short, got Windows 7 64Bit Ultimate RTM.
Clean install on my pc at the weekend, got 3 harddrives now.
Partitioned my 500gb so ive got 100GB for the OS/programs and the rest as 'F' drive for my games.
Installed Fallout 3 onto the F drive using custom install. Then updated to 1.7. Installed all the DLC's, then installed the unofficial patch from Fallout Nexus.
ran the game and it installed and played fine.
I did not put in any compatability mode, just double click the icon and it plays.
Ive now installed loads of mods and it seems ok, few crashes when im walking around Megaton but thats about i for now.
I find that i have less problems with games if i install them on another drive...away from the windows files.
Also, try this
Game Booster | Faster Play, Free Download | Free Game Accelerator Download
I find it works well on windows 7, might help you as it shuts down background services etc...