Need help choosing one of these cards

Dom_79

Distinguished
First off, my rig:
Dell OptiPlex 760 MT
Intel core 2 duo E8400 3.0Ghz
4 Gb DDR2 800Mhz Ram
Corsair CX500 PSU
1920 x 1080 resolution
(Win 7 64 premium)

Here are the cards:
EVGA 01G-P3-2642-KR GeForce GT 640 Super clocked 1GB 64-bit GDDR5
Link to Newegg: http://

EVGA 02G-P4-2643-KR GeForce GT 640 2GB 128-bit DDR3
Link to Newegg: http://

I'm tempted by the first one for a few reasons: The price (10$ cheaper, budget is TIGHT!), DDR5 (but it's only 64 bit! ARRRGH!) and lastly it's factory Over Clocking - pretty sweet but I can't figure out if that will compensate for 64 bit memory.

The second seems a safe bet but, if there isn't much difference, I'd like to save 10$

This card will be used for gaming to the best of my CPU's abilities