I'm planning on getting an HD 4670 since my x1300 pro ain't cutting it. I'm just wondering, will my Pentium D925 cause a huge bottleneck for this card? Cause it seems my mobo can't take a better cpu.
Generally speaking no, but since you haven't provided which games your going to play or what resolution, no one can say for sure. Some games your PD will struggle to run regardless of what graphics card you get, and if you game at high resolutions, the 4670 is going to struggle. It all depends on the situation.
Well I'm hoping to play games like Alien swarm, left for dead 2, cod mw2, and crysis on medium-high settings at 1024x768.
Everything will run pretty smooth at that low of a resolution. The Pentium D 925 is weak in todays standards of a processor , but its no slouch still it should handle most games with very playable frame rates at a reasonable res.