Please help me decide on how many GBs I need for either a PS3 or XBOX360?

Xbox makes it astoundingly easy by giving you the options of 4 and 250gb. Obviously, there the 250gb model is the best choice.

I had one of the old 80gb PS3s and I never came close to filling it up. You'll probably be safe to buy the smallest HD size available.

As for RPGs, I'd go with Elder Scrolls IV: Oblivion and Dragon Age. Both are truly epic and will keep you busy for hundreds of hours.

Man to be honest, just go with the 120 GB. I have the 120 GB PS3 slim, and it's amazing for me. I don't even have a quarter of it full and I have loads of games to play on it. I'd say get something higher if you're a video game junkie, but for the average joe, 120 is perfect.

As for RPG's, I'd definitely recommend Fallout: 3, Fallout: New Vegas, Dragon Age: Origins, Oblivion, and there are few exclusives for the PS3 and XBOX that you will have to decide on your own.

Not to sound like a PS3 FANBOY or anything, but if you're deciding between XBOX and PS3, just note that PS3 is the only console currently that can output 1080p HD resoulution, AND it can play Blu-Rays which means less disks, and more HD ;) However, XBOX does have better online, but it's not FREE! :D

250GB is insane bro, my cousin has a 500GB PS3, he took out his laptop HardDrive. but ive had the 40Gb ps3 or like 2 years now i havent filled it up and i have close to 12 games so just go with the 120gb

I advise 250 or more for BOTH