I am presently dual booting 98se and XP on my tbird. Has been like this for a few months now. I was going to dump 98se but am going to keep it in a dual boot config as a few games that do not work in XP @ all or very buggy.
Pentium 3 1000 @ 1100 ( windows 2000 server), Abit bx-133, 256 Mb Mushkin Rev.3 cas 2-2-2, ATI Radeon
AMD Thunderbird 1.4 @ 1.63 (24/7) IWILL KK266R , Corsairs pc 150 cl2, Leadtek GeForce 3