Fortunately, there's a way around that. And who better to provide the info than Microsoft themselves? The KB article is simple enough to follow. I'll just reproduce the gist of it here:
- Backup the Fp40ext.inf and Ims.inf files. They're located in the C:\Windows\inf folder.
- Find the string referencing the Windows edition in a section labeled with [Strings].
- Edit the string to the edition of Windows on your CD.