May I suggest one thing? Go down to the store and cruise the game section. You will probably love whichever system you get. But not all games are duplicated on both systems. So cruise the games for both machines. Figure out which games you want. And that may decide the console.
you will be very happy with either one. PS2 is $180. The Xbox is $150. The Xbox controller is ten dollars more, and you will want a second controller for friends, but then you don't have to get an ethernet adapter or a memory card. Hmmm... I would be willing to bet the PS2 has to drop in price soon to match this.
Personally the games on PS2 are funner IMHO. but then... the XBOX looks cheaper.