Slow startup on xp sp3

i know this has probably been asked in several languages and different ways before, but i am having a problem with a slow startup. before you click back and ignore my post, hear my piece.

asus p5q motherboard
q6600 quad core chip
4x1Gb Gskill ram
evga Ge Fore 8800 graphics card
500gb main hard drive
2x320 gb hard drives (not in raid configuration)

my processor is custom built. the only problem i have is at startup. once it boots it's quick. the windows logo takes a while to cycle through, as well as the "logging on" splash screen. i have ran ad-aware, norton, avira, regcure for the computer and it improves a little but not that much. i've updated my bios, done mscofig via start>run and disabled all unnecessary startup programs. i've done everything i can possibly think of but to no avail.

short of reformatting or starting with a brand new hard drive, what else can i do?

thank you.