your request has not been unheard by me, but frankly I don't know of a solution, because I am also searching for the main video editing application. Still trying out Edius, Avid Media Composer . . . maybe SpeedEdit could be something interesting, but I haven't tried yet as the installer is too big to download just for a test.
So I can only repeat what I know is very fast:
Premiere Pro 2 or CS3 -> After Effects 7 + Nucleo Pro 2 on XP 64-bit.
Inside Nucleo, you can configure perfectly how your resources are used. Full rendering, background rendering, how much RAM should be left free, how many CPU's should be used, Render Job Manager . . .
It really depends on what you want to do. If you shoot with your camera, a simple and quick editor is needed. So I think a solution with Avid (there are cheaper applications that probably will be sufficient) would then be a good choice. On the other hand, when you want to import an image sequence into Media Composer, it takes sooo long while in Premiere it is fast imported. So Premiere is also a good choice if you want to do a bit of compositing without using other software.
Keep us informed about your progress, that would be a valuable information for the forum. Have a good time and - hehe - buy another machine to
really render in the background. That would be nice, wouldn't it?