I had a similar problem last night when I installed XP via boot camp. I assume you're trying to install drivers for windows from Leopard disk. I was very frustrated, but there are a few things you need to double check.
You must have windows xp service pack2 because apple dirvers look for an updated windows installer that's available from SP2.
Make sure you don't use MacDrive software. I haven't used it but I've heard there's an option that makes windows think you inserted OSX-compatible disk.
In my case, I didn't have mac drive 7 and I have SP2 installed. So last night, I just turned the computer off. For whatever reason, when I tried to insert the disk again it, windows reconize the dvd and it worked.
One thing I changed though was in OSX, I went to system pref and changed OSX as a default boot. Not sure if that has to do anything with it. My macbook is onle a few days old, I will test if my superdrive has any issue.
good luck