I tried to do a clean install using my Gateway supplied version of W98 and the XP upgrade cd.  I knew it would ask for the old cd, but didn't think it would be a problem- I have it, it's mine, it's registered, it's clean. About 45 seconds into the procedure it asked for the prior version CD, I popped it in, XP said there was nothing on there.  Tried again. Tried again from  scratch.  Same result.  MS tech Support said I just had to enter my key.  I asked where.  Thirty minutes on hold he comes back and says he was wrong, I needed a CD, and get this: I should get another copy from Gateway!  They offered to send me a copy of W98SE, but it would take two weeks. Hey folks here's the bottom line- to do a "clean install," you probably have to reinstall your prior (OEM) version before you can use the XP Upgrade package.   Hello Microsoft- isn't that just about the entire population?  Hello Microsoft why can't Windows XP EXPLORE a cd?  Hello Microsoft why can't I enter my old key anywhere?  Hello Microsoft, ever hear of Overnight Delivery?