I'm trying to install IIS on Windows XP Pro. When I run the install it asks me for "Windows XP Professional Service Pack 3 CD". I downloaded a disk image of "Windows XP Service Pack 3" from Microsoft and successfully burned a CD, but apparently that isn't the disk it wants. I find no reference to a "Pro" version of SP 3. What do I do? Is there a "Pro" version of this service pack I can get from Microsoft?