I use Sony Vegas Pro 11. I have a Core i7-2600K @ 3.4ghz w/16GB RAM and a EVGA GeForce GT430 video card (Cuda cores make a difference with VP11). I am blown away by how fast my renders go and how easy it is to edit MTS files directly.
Last night I rendered a 32 minute HD (1080p) piece in less than two hours, using lots of FX (color correction & brightness/contrast) and large Digital Juice assets (some backgrounds were > 6GB, most in the 3gb-4gb range as quicktime files).
As a rule, the biggest, most powerful CPU you can get today is where you should look – It will make a difference and help you put off buying/building another system for a year or more (my last box lasted ten years because I did this – It still is OK for general office use).
