I've been running Vista on my Core2Duo E6600 with 2GB RAM desktop for a few months now, and I much prefer it to XP. My install is very stable, and I have had no software or driver issues at all.
The only possible issue is a warning whenever I load up Photoshop Elements 4 and Vista warns that this application was not designed for Vista. I've never had any problems with it though.
My Celeron M 430 Laptop which came with Vista is sluggish, but again no problems with stability. However, I'm just about to put Ubuntu Linux on it, for no particular reason other than curiosity.