I have been running Windows 7 RC on my laptop for about 3 weeks now. Not a single problem. All drivers are there, just plug & play! The system runs MUCH smoother than Vista did. I was supposed to install Ubuntu on my LT, but decided to test W7 and ... quite frankly I only miss linux a little bit
The start up is faster that Vista. I don't know about running W7 on old machines. My LT have 4GB ram, Pentium T3400 CPU and Ati HD3470 graphic card. Works like a dream. Of course not as fast as Ubuntu, but not very much from it!
If you are on Vista now and like it, you will love Windows 7. If you don't like Vista you will still like W7.