I use ESET. I've probably tried all of them except for Microsoft's own.
Asus G74SX-TZ226V:
Standard Setup: Intel i7 2670QM, GEFORCE GTX 560M 3Gb, 8Gb Ram, 750Gb Harddrive, BD/DVD-RW.
Future Setup: Kingston 16Gb Ram, Kingston HyperX 120Gb SSD, Seagate Momentus XT SSH 750Gb.