If you're handy, do as vista user 43 suggested:
Get a disk imaging program.
Partition your disk so that you have one or more
data drives.
Clean up all the ads, "shovelware", waste, etc. from Vista.
Set it all up just the way you want it.
Then create a disk image and store it on your data
partition. Also copy it to one or more CDs or DVDs.
When you need to restore, just boot to your disk
imaging program and restore your personalized version
of Vista, rather than the ad-encrusted mess that
came with the machine .... and which will take all
day to clean up again.
BootIt NG is one option for disk imaging. I bought it
for $35 and have never had a problem with it. (Though
I haven't tried it with Vista.) It does all partitioning
operations plus disk imaging and allows you to make a
bootable CD. I've created clean disk images of Win98 and
XP that fit easily on one CD after the unnecessary bloat
is cleaned out.