Well i have already got it. i have family that works for M$.
The first thing i noticed was the install takes forever and the installer just sits there for a good 20 minutes doing nothing. The OS itself is fine. it is solid as a rock. Runs fast. We have one test bed machine with Business edition at my school district. and it runs on a conroe powered laptop, but only has 512mb of ram. it runs slow. My best advice is have a gig of ram minimum and its good to have a dual core cpu too.
My specs are in my sig. Ive actually looked at the numbers and Vista uses about 10% less ram than XP does, on the same machine. I think it may be because Aero Glass is hardware accelerated 3D, its almost like it doesn't touch your ram at all, which is really nice.