This project consists of compressed 640×480 video footage. These small video files were being eaten alive by the massive 1090T hexa-core processor and 8GB of RAM. Premiere Pro CS5′s increased performance with multi-core systems coupled with bleeding fast hardware will make fast work of any simple projects such as this, not giving the GPU enough work to really make a difference. These results do suggest that if you’re editing small-time video footage, you will not benefit much from using Mercury Playback.
So assuming u not leveraging on Mercury Playback Engine:
if things change nab something like a 1GB GTS 450 ^^
For simplicity sakes on the mainstream desktop platform lets just approximate it as a 3.2ghz OCed E4700 (though your was on 90nm fabrication process and this 65nm) hehe http://ark.intel.com/Product.aspx?id=34441
Even at this low investment price point the improvement is monumental to say the least