SC3 and MegaMan X8 are both awesome games. But Megaman X7 is almost universely argeed to be the worst MegaMan X game.
And as much as I love SC3 and MMX8. I don't think they're enough incentive to go and buy a buy ps2 just for those two games. If you like wrestling Smackdown v. Raw 2006 is good. And if you can find it Red Faction 2 is one of the best FPS games ever made, and a used copy is about eight dollars.
So What I was going to say is. SC3, MMX8, SvR 2006 and RF2 all put together is enough incentive to get a ps2. And if you like Grand Theft Auto you can toss that in there too.