When I talk of "bootup" I'm talking from the time I turn on the computer to the time EVERYTHING is up and loaded and drive activity stops, which is usually after my Yahoo widgets load up. I've got tons of (useless?) crap loading on this system (over 60 processes running after boot is finished!). I agree it's a long time, and I'm sure if I took out a lot of these services and applets it would be faster. The A7N8X system is still using an ATA boot drive and I tried moving my OS to SATA but found it impossible to do without reinstalling the whole OS (and all its software...) from scratch.
FYI, the C2D in my sig boots up in about 30 secs. It's my work system and I keep it lean and mean: there's less than 25 processes running after boot is complete.
I find Windows XP desperately tries to be "fast" at bootup by bringing up the desktop way before every applet and service is up and running, so I don't count boot up as time to the desktop.
At any rate, none of this relates to the question of why, all other things being equal, a boot would be faster with a better power supply...