Ezeduzit

newbie question
I bought Ultimate w/SP-1 OEM 64 bit
I currently have Home Premium 64 bit.
Can I just install Ultimate on top of Home Premium---or should I uninstall it?
Any pointers appreciated
Ezeduzit
;o)
More----
If I uninstall Home ver during installation of Ultimate, why would I need to keep the recovery copy of Home ver on "D" that came with the computer? Shouldn't I get rid it and free up that partition for other use... then just make a complete computer recovery copy and store it on the USB external drive ? I like what I have read a litte about the Maxtor One Touch backup--- but have never used it. I presume it will do a complete computer back up ?