When I first built my computer I was running and AMD 3000+ and on the first Windows install it literally took 10 seconds. It was insane. That was about a year ago. Since then it's just gotten slower. Right now it will take about 20- seconds to get into Windows and another 20 seconds for everything to load.
On a spare computer, P3 733MHz im running a modified lite version of XP Pro and it boots in 20 seconds flat.