Major crash

I have just had a major meltdown where my PC refused to let me in.
I allowed MS updates to install and as usual it asked for re-boot so i let it that's where the problem began.
During start up the boot screen asked if i wanted to start windows normally,this screen does not often show but OK i boot normally, no chance! it goes through the motions of booting and in the end returns to the boot screen.
After trying ALL options (safe,safe with networking and so on) I still can not get it to complete the boot sequence, so it's time to think :crap it has wiped my HD.
I put my recovery disk in and selected repair,I then get the repair completed screen.
Re-boot and the next surprise is i get the boot screen with 2 OSs Vista home premium and Vista ultimat(recovered) so i click Ultimate it go's into boot and then asks to activate with the OS code.
I know i have the code some place (but where?) so i re-boot and select Vista home premium it starts to boot and then goes back to where i was in the beginning (safe / normal /with networking ) and will not come out of the cycle.
I put my OS disk back in and select boot from DVD, when i get the screen i select System restore and after what seemed an hour it came up so i restored to just before the MS updates and after a while it re-booted and then came the boot screen with the 2 options Vista home or Vista Ultimate just as if i had dual boot.

I booted into vista home and it loaded, so i check with everest what i have got and it tells me Vista Ultimate so now i am really baffled as to what happened here.
Any ideas folks???????

PS i have not dared to re-boot since i got it working (chickenhttp://smileys.on-my-web.com/repository/Animals/animals-13.gif)