[quote name='Dark Lord Greg']if I recall the GOTY is just the regular game wit ha 2nd disk that includes all the DLC which you install on your hard drive so you can use your Fallout 3 regular save. At least thats the case with the 360 version[/QUOTE]
QFT
Though I think the game disc does look different, ie says GOTY Disc 1 on it, but otherwise I believe it's the same disc. The second disc has all the DLC on it which you put in the Xbox 360 first to copy off the DLC. Then put in the game disc.
The game "scans" for the DLC and when you start the game you get messages that prompt you to go to areas where the DLC missions are. That way if you have the completed the main game the game will tell you where to go next.
I bought this game late last year for $29.99, didn't really start playing it until a month or so ago. I love this game! One of my favorite games by far. It takes awhile to really get into it, so stick with it because eventually it will "click", it did for me anyway. Also a little friendly advice, the Fallout Wikia page will help you greatly, but try not to absorb too much at once, or you may feel overwhelmed, lol.
As far as Oblivion comparisons go, I have played Oblivion, and I have to say I like Fallout 3 a lot more. It's a matter of preference, really. The games kind of play the same, but Fallout 3 feels...fresher, I guess.
Anyway, for $20 you can't go wrong! I highly highly recommend this game.