Cast
2
well i went through and tested a bunch of free ones to find one that had lower resource usage and between those two:
Ram / Page File
Avast 664 / 533
MSE 720 / 623
No AV 648 / 513
running Vista Home Premium(x86)3gigs of ram with an amd turion x2 and those were my results, idk how well they would do for yours.
before anyones asks yes my system shouldnt have any problems running pretty much any av but when you play graphical games or fps you usually go with the lower one and the one you like the best performance wise.