FYI - Vista minimum and recommended Specs.....
Minimum Requirements (Vista-Capable PCs):
800 MHz Intel-compatible processor
512MB of RAM
DirectX 9.0-Capable Graphics Processor
20GB HD
Recommended Requirements (Premium-Ready PCs):
1 GHz Intel-compatible processor
1GB RAM
DirectX 9.0-Capable Graphics Processor, with 128MB graphics memory. (64MB of graphics memory to support a single monitor less than 1,310,720 pixels [no more than 1440x900]; 128MB of graphics memory to support a single monitor at resolutions from 1,310,720 to 2,304,000 pixels [no more than 1920x1200]; 256MB of graphics memory to support a single monitor at resolutions higher than 2,304,000 pixels [more than 1920x1200]).
40GB HD with at least 15GB "free space"
I've seen, used and been playing with Vista Beta for a while - if you want it to look nice, and have all the functionality, you'll need a powerful pc.