Rebooting a Windows computer is a pain in the neck and depending on the OS, hardware or software installed, it can take quite a while for the machine to boot up and be fully responsive. Averages run around one and a half minute. first the BIOS loads, and then eventually Windows.
So, what if you could just restart Windows, without restarting the BIOS?
"Sometimes, you need to reboot Windows (e.g. when installing new
software), but there is no need to restart BIOS, too. However, the
default is to reboot both. (That’s called doing a “cold boot,” rather
than a “warm boot.”) There’s a trick that works on both XP and Vista to
get it to do a warm boot instead, thus saving you 30 seconds per cycle"
Read more: http://www.codejacked.com/
Update: Apparently this trick only worked in older Windows 95/98 machines. Details here.