Turn on built-in firewall (if you have a router, skip this step)
Install only the drivers that came with your hardware; however, if there are new versions for them (i.e. nvidia stuff), use those, but do not install "extra" drivers that the manufacturer has on their website. Only install the drivers that are required for the product to function.
Windows update - Service pack 1 / 2
WU - all other service packs
WU - critical updates
WU - drivers, only if it is for a piece of hardware that did not have drivers (i.e. lcd monitors)
WU - recommended updates (optional... obviously)
configure windows with all the settings you want (or import from a backup; disable the builtin firewall if you enabled it before WU)
Install anti-virus program
Install a firewall (if you need a software firewall)
Install all other programs and hardware that requires software installation before you can plug it in
Kinda confusing at parts. Let me know if you want me to expand