Problems with my hardware.

first of, my setup.

OS: win xp pro sp2
Motherboard: MSI P45 Diamond
CPU: Intel Core 2 duo E8500 (stock)
GPU Radeon HD4890
Ram: pc10666 2+2 gb (dont renember the brand)

Sound card: (dont matter, but anyways) Creative SB Live! 24bit (from my first pc, Several years ago)

OK, so here is my problem, 2 actually..
first of, "booting"

my pc will not boot on the first try, nor the 2nd... it always boots after x number of times.
what happends is: i get past bios screen, and on to the loading screen for windows, then it freezes, same thing happends 5-8 times, then it boots and works "almost" perfectly.
Ive noticed that if i boot, and dont do anything after it freezes, just let it run for 5-7 minutes before i hit the reset button, it boots normally.

as far as i can work out, its either the HD or my os thats corrupt, but its wierd that my HD works perfectly other than when im booting.
(if i reboot after it has booted sucsessfully it boots like normal)

2nd thing thats not working at all is updating GPU driver, when im about to install the latest driver, it seems to be going fine up to a point, then the HD powers downs and my pc reboots. cant work out why.

i have never used the os im using now, so i fear its the problem, used my old xp pro on the same computer earlier and worked, other that it was really old so it didnt work 100% with my new parts.

Tired right now so im sure im missing some details, anyway, thanks for any reply that might solve this problem.

(i have NOT tried to format and install another os verson, have some backuping to do first)