I've installed XP on 3 of my machines with great success, but one of them takes a very long time booting, over a minute. There is a long period as the "chaser light" scans across the screen that there is no disk activity at all. It scans about 20 times, halts for ~5 seconds, and then scans at least 10 more times before booting. After booting there are no noticable performance problems; it's just that delay at the beginning of booting.
This even happened the first time I booted the machine while installing.
Is there a known issue with certain chipsets, video cards, or other hardware? This is all I can think.