Windows Vista upgrading from vista prem to ult

i have vista premium 64 installed and want to upgrade to ultimate 64 but wont let me do an upgrade only clean install. it says upgrade disabled and at the bottom it operating sys installed is newer than the one im trying to install. the dvd i have is 2 years old because my old pc was xp and tried to upgrade and failed badly. it goes on online to check for updates but it seems like it would update to the latest version before install. so i figured i could unistall all windows updates and try again. thats one option. the second is to get a new one from anytime upgrade but who's to say it won't do the same. thing. is anytime a download or a shipped dvd if its a download it seems like it would be the latest version. i don't know? any sugestions before i try to ***** up my pc again, lol
thanks
added note: i can't find sp1 to unistall from installed updates.

 

case closed. microsoft is sending new dvd with sp1 on it. that was the problem my sys had sp1 installed and the disk didnt.