I purchased Fallout 3 Game of the Year edition a couple days ago. I installed the game and it's expansion disk without any trouble. The game runs decently without any slowdown or stutters, except:
Every couple minutes the screen freezes and I can't do anything. The ambient sounds continue to play. After 20-30 seconds, it "unfreezes" and gameplay resumes. It doesn't appear that any time in game has passed as NPCs in mid-sentence just continue where they left off. Then it happens again within a couple minutes. My computer responds immediately to Ctrl+alt+delete and I can shut down the process quickly.
I have an NVIDIA GeForce 8400 GS video card.
2.6ghz dual core processor
2gb RAM
Windows Vista 32-bit
If you require any more information, please let me know and I'll be happy to provide it.