I have an HP Pavilion 510n, 1.2 ghz celeron, 512 mb sdram and am currently using a GeForce 2 mx/mx 400 PCI ( I don't have an AGP slot ) 64 mb video card. Some of the games my kids use on the system are RollerCoaster Tycoon 3, Sims 2 and Unreal Tournament. My question is would I see much improvement in switching to a 128mb or 256mb video card or should I just start shopping for a new PC?