I've had three computers in my lifetime: 1989-1992; Packard Bell with Win3.1, 1992-2003; Compaq Presario with Win98FE, 2003-Present; IBM with WinXP.
The Packard Bell with 3.1 was awesome (though by today's standards, slow and bulky); it never crashed, never had any problems of any sort, and the only reason we got rid of it was because my mom won $7k at the casino and bought the Compaq for $2200. That thing was the bane of my existance. It sucked up every megabyte of RAM for seemingly no reason, crashed at minimum twice a day, and to my knowledge, we performed fourteen formats on it because SOMETHING would occur that would render it useless. Christmas last year, it finally gave up for good, and we got this IBM. No problems whatsoever. It has the stability that 3.1 had with the massive technological advances that have appeared in the last fifteen years. I absolutely love this thing.
Case in point: WinXP r0x0rz your b0x0rz.
Compaq server hardware seems to actually be good, and as stable as most anything else running Win2k.
Read that out loud. Now tell me it doesn't sound like you are calling windowsXP slow loading and bulky. If you say something that can be took in a funny way, someone is going to point this out. So don't go on the defencive over something so small, just remember this leason and try again another day.
What I gather from that is that you placed XP in a group of slow loading, bulky coded OS's that are all older than something, or possibly just old in general. XP is however, the best of the group for some unstated reason.