Looking for a new monitor

AMD Athlon II X4 @ 3.1Ghz, MSI 880GM-E35 (MS-7641), EVGA GeForce GTX 550 Ti 1GB, Kingston HyperX 8Gb, Coolmax 600W, Coolermaster 430 Elite, Microsoft Sidewinder X4 Keyboard, Logitech Gaming Mouse G300
 


I can't recommend IPS panels. I get motion sickness with low response screens, so I'm not well versed with IPS, which have lower response times and lower refresh rates. There are quite a few people around here that should show up to give you their recommendation though.
 
The BenQ XL2420T is widely regarded as a great 120hz monitor. It's 24"
The BenQ XL2420TX includes the 3D Vision 2 kit, if you are at all interested in it. I find it awesome, personally.

The ASUS VG278HE is something a little unique, but also good. It supports 144hz and 27". This is particularly good if you have the 3D Vision 2 kit, as it allows 72hz 3D gaming.

They are great monitors for 120hz or 144hz. I mention the 3D Vision because if you are going to have a 120hz monitor, 3D Vision is a nice extra.