DDR2 is faster than at DDR in a sense. You do not NEED DDR2 memory at all for gaming. You do however need it for the new CPU's such as C2D's and some of the X2's.
So no you do not NEED it unless you plan on upgrading your CPU.
well im buying battlefeild 2 and right now i have a shity monitor but my comp speed is more important i have a 15" crt old peace of crap. so FPS and RPG's. and any recomendations on fast paced run and gun type of FPS?