I know eventually the push will be to go Vista and that's fine.  But for the current moment, and the next project, I'm looking to replace my XP Pro to take advantage of the 4GB of RAM I have for running MC 3.0.  Am I safer with XP 64 or Vista 64?

BKLDOG - you had made a comment in the past that Vista was not using the GPU or something on the nVidia cards like XP does, thus costing some performance.  Still true? 

cancel that - i see xp 64 isn't supported.

 XP pro 64 is not supported. Your only choice for a 64bit OS is Vista Business 64bit.

It actually runs very smooth on it (so far!). I have installed it a few days ago and havn't found any bugs yet (but I am sure there will be some).

thanks AquaPix.

BLKDOG remarked that Vista doesn't take advantage of the nVidia GPU like XP was able to.  Have you seen this to be the case?

I'm just trying to decide if I'm better off with XP Pro / 3GB usable memory or Vista 64 and 4GB.  Maybe the Vista route would only be worth it if I jumped to 8GB or so. 

 ... damn, you beat me with the reply to your own post

 Well to answer your question, I have put 8GB of RAM in my system and it really seems to speed up things. I haven't done a benchmark test, but there doesn't seem to be any performance drops, though RivaTuner and ATITool seem to have problems to overclock with the currently supported nVidia Driver (169.47 me thinks). I hope that Avid is testing a newer driver for the next MC update to resolve this.