I sold my copy of regular Fallout 3 today so that I could purchase GOTY (to get all the DLC). Long story short, the GOTY version keeps freezing at launch and I cannot even get to the main menu! I've tried it with and without the 1.01 patch, and still nothing. What is going on? If I can't fix this soon, I'm going to have to return it and get my money back...

Let me get this straight, you bought FO3 goty but got also a patch 1.01 for it? This is on the PS3, right? I'm kinda confused because I got the goty (uk) a week and a half ago, played it without any freeze since then (~17h) and overall a very stable framerate ... and I can't recall there was a patch available. Granted, I'd have to verify but I'm pretty sure there was no patch for it.
Did you remove _all_ the data from your previous FO3? I read that users have massive problems with this game when keeping game data and/or saves from their standard version.