If you choose to purchase an upgrade version of Windows Vista to upgrade XP, you will no longer be able to use that version of XP. Either on another system, or as a dual-boot option. The key will be invalidated, preventing activation.

From Vista’s EULA found here:

Sourced from Tom Coyote

So save yourself some pain and angst, pay for the full version and still have two operating systems...

Good Info Arctos!

Although i would never buy upgrade versions anyway. M$ have also done some stupid licensing on OEM copies so that you cant upgrade much basically.

thats good info. i didnt plan on buying it now but...ill remember that in the future

lol btw, i like your signature.

according to the Eula you can only install the full version 2 times. not sure what the mag was I read this in ( e-week or computerworld) but this is reason enough for me not to buy it right away gonna wait till the first SP comes out to make a fair judgement (most of the kinks should be worked out by then) can't see spending big money on a untried system (beta testing seemed to bring out tons of other issues) Don't want to turn my"WOW" into "MOM"

uhmm... I bought the upgrade version of Vista and only had the OEM version of XP Media Center and I did a full install and can run both XP and Vista...

Thanks for the tip that really sucks!!!! I would have thought you could use both. Iook like I'll be getting the full version. I wonder if microsoft is already trying to fade out XP as they will sell a lot of upgrades.