Not to rehash past discussions here too much, I will reiterate that there isn't a price premium for Apple computers when compared to another OEM providing a complete system and warranty. They do lack the same variety of different computer models that other vendors offer, and they do lack a midrange expandable monitorless system. That market is a shrinking one though, and at this point I don't think it's a market segment Apple will address now.

To answer your original question, it looks like you have to have an activated install of Windows XP, Vista or 7 RC present to use an upgrade disc.