How to upgrade Windows 7 Profession to Ultimate with a Technet Key?

When I installed Win 7 pro using my technet key, I thought Ultimate did not offer anything substancial in addition, so I just went for Pro. Now I find out Pro does not have Applocker ^%$#*

Is there anyway to upgrade to Ultimate using a Tecnet windows 7 ultimate key?
Will it install the bootloader again? Do I need win 7 ultimate discs?

I have the system triple booted with XP, win 7 and linux, and getting the bootloader to work with all three was a bit of a pain, so I'd like to avoid doing the bootloader again if possible.

 

Anytime Upgrade will allow you to upgrade to Ultimate without the disk (as it is already there) and using Technet key. Otherwise you will need a disk

 

What disc is already there? Win 7 pro?

And sorry to be daft, but how does Anytime Upgrade work? I dont see any instructions on http://www.microsoft.com/windows/windows-7/get/anytime-upgrade/home-premium.aspx

 

I expressed myself poorly, I meant Ultimate is already on the computer (just a key away)
Is there an anytime upgrade link on your comp? If yes click on it and follow instructions and 10-15min later after reboot there will be Ultimate

 

Oh cool, thanks, I really need to explore my systems more

 

Woooooaaah...that was fast

EDIT: Can I now use the old win 7 pro key on another system?

 

yes you can use the pro key on another system. as long as its only on ONE system at a time. though you may have to use the phone activation method which takes only minutes..just make sure to tell them its only on one system when they ask you and if they happen to ask why just say you had to swap the mobo or the hard drive.. no big deal

and to add more info go to anytime upgrade in control panel (not sure if you got it to work or not..if not......) open it. it will ask for your new lic key enter the ultimate key and proceed with the upgrade. its really very easy to do.. if i can help more let me know