Which Windows XP Pro Version

I am just beginning to install and setup Parallels Desktop on my new MacBook Pro. I will need to purchase a copy of Windows XP Pro and naturally want to spend as little as possible on Windows. I was looking at one of the OEM copies of XP Pro available at a number of web sites, when I read a note indicating OEM copies do not work with Parallels. Is this true? If so, why? OEM versions are considerably cheaper than the so-called full versions. Could someone explain the difference?

Thanks for your help and please forgive this neophyte question. I've been driving Macs since 1984 but I'm not very deep on Windows.

Manny Key

 

I got an OEM dvd at a local "build your own computer" shop and it worked fine

Sp2 is essential

Hugh W

 

OK, thanks.

 

I'm not 100% sure of the difference in the 2, but OEMs aren't supported by Microsoft. If there's a problem with it, you have to call the company that sold it to you. Why it doesn't work with Parallels? You got me