For really good performance, I'd recommend this:
1.5GB of RAM (512MB will work, but not ideal)
Processor that supports 64-bit preferably an Athlon 64 or equivalent
An AGP 8x video card or PCI-Express x16 that does everything Andre said,
except I'd recommend a minimum of 256MB of VRAM for good performance,
especially with higher resolutions (I'd recommend an NVIDIA GeForce 6600 or
higher or ATI x700 or higher for the best performance with higher screen
resolutions, although if you're using low screen resolutions, an FX-series
NVIDIA will work fine.)
A SATA hard drive is recommended that has at minimum, 20GB free (8 of which
is used for Vista as of now)
You will need a DVD drive
For strong and good, but not perfect performance, I'd recommend this:
1GB of RAM
AMD Sempron 64 CPU (preferably with 256k of cache)
An AGP 8x video card that has 128MB of video RAM and is an FX-5600 or higher
or Radeon 9600
An IDE hard drive with 8MB of cache
DVD drive
For my recommended minimum configuration to give you at least decent
performance, I'd recommend this:
512MB of RAM
AMD Athlon XP (Sempron socket A) or equivalent Pentium4
An AGP 4x motherboard with an 8x capable video card with at least 64MB of
video RAM. An FX-5200 or Radeon 9500 is the minimum card you'll need as of
now to get Aero Glass for a desktop PC. Any card below what I just
mentioned probably won't run Aero Glass.
An IDE hard drive with 2MB of cache (ATA100)
DVD drive
Keep in mind that Vista will probably work on systems slower than what I
mentioned for a minimum configuration, but for at least decent performance,
I'd have at least what I said was the 'minimum configuration'.
