Constant reboot during boot (no windows)

Ok my mate has got him self into a bit of a pickle.
Afew months ago we both got vista 64bit and seems he is having quiet afew dramas but the most recent is as follows;

Install and updated through windows update (7:13pm Tuesday 26/6/07). Restart required.
Computer did first reboot and then reconfigured the disk driver (new NVIDIA sata drivers in update) and I have read up on this and also done the same update, so i know this was reconfiguring the system and interprets the HDD as a scsi device (has given me no dramas)
Anyways, second restart required.
Upon booting the bios is normal and everything is fine until the window splash screen where it suddenly reboots... continually, for eva???

He has tried safe mode, last known configuration, start windows normally... he cant get online cause he cant do anything to access his vista - short of reformatting and loosing all his data!

Hope someone can help me to help him.

Cheers
Anthony

Ok well lucky I looked into the installation cd abit further as i found its got a repair windows (via system restore) function after the first languge selection prompt.

So he is back in Vista now as it created a restore point before it installed the updates.

But still this problem should be addressed by microsoft...