Best choice for me?

I've been trying to find parts for my first build, and I'm stuck on which GPU to buy.

This computer is going to be mainly used for gaming. I want the games to be really smooth even while recording with fraps. (I want the average fps to be around 50 for any game).

My specs (so far):
CPU: AMD Phenom II X4 955 Black Edition Deneb 3.2GHz Socket AM3 125W Quad-Core Processor HDZ955FBGMBOX -
RAM: G.SKILL Value Series 8GB (2 x 4GB) 240-Pin DDR3 SDRAM DDR3 1333 (PC3 10600) Desktop Memory Model F3-10600CL9D-8GBNT
HDD: Western Digital Caviar Blue WD5000AAKS 500GB 7200 RPM 16MB Cache SATA 3.0Gb/s 3.5" Internal Hard Drive -Bare Drive
2nd HDD: Western Digital Caviar Blue WD5000AAKS 500GB 7200 RPM 16MB Cache SATA 3.0Gb/s 3.5" Internal Hard Drive -Bare Drive
OS: Microsoft Windows 7 Home Premium 64-bit 1-Pack for System Builders - OEM
Case: Antec Three Hundred Illusion Black Steel ATX Mid Tower Computer Case
Motherboard: ASRock 870 EXTREME3 AM3 AMD 870 SATA 6Gb/s USB 3.0 ATX AMD Motherboard
CD Drive: LITE-ON Black 24X DVD+R 8X DVD+RW 8X DVD+R DL 24X DVD-R 6X DVD-RW 12X DVD-RAM 16X DVD-ROM 48X CD-R 32X CD-RW 48X CD-ROM 2MB Cache SATA CD/DVD Burner - Bulk - OEM
PSU: CORSAIR CMPSU-750TX 750W ATX12V / EPS12V SLI Ready CrossFire Ready 80 PLUS Certified Active PFC Compatible with Core i7 Power Supply

Woops forgot the resolution, it will be: either 1920x1080 or 1680x1050
I have yet to decide on a monitor because I have a spending limit.

I don't want it to be too expensive so I've narrowed it down to 2 choices. I also hope they are compatible with my current system.

Nvidia Geforce GTX 460 1GB
2 Nvidia Geforce 9800 GTX+ 512mb