I think Spore was way overhyped. It was a game that, basically, showed macro evolution in a fun kind of way. You start as this microorganism and slowly evolve into a being, then a colony, then a society, until you conquer space and raid other planets.
It seems like all the game modes are just a long lead up for space exploration mode. It was kinda fun, but I only played it on a friend's pc for a week then didn't bother playing it again.
My favorite games, though, gotta be Gears of War and World of Warcraft. On a high-end pc, WoW looks just so amazing. Another good MMO is EVE. It really requires a top-notch pc. The game runs on 3 or 4 servers that all have up to 40,000 people on them at once. You're playing with 40,000 people at the same time! The game is so expansive, too.