I bought a new Dimension XPS a few days ago with 2 SATA 80g HD's and I want a dual boot. 1 hd has win xp pro and the other is empty. I formatted the second hd and made 2 partitions. 1-30gig partition with fat32 and the second with ntfs. When I try to install FC3, it tells me I have no hard drives and exits the install. I have even tried disabling the XP hd and then installing FC3, that didn't work either, same results as before. I have already installed FC3 on another hd in a laptop and it worked just fine but this XPS is a little different. Any help would be appreciated thanks...

Some distributions have better support for SATA, FC does not appear to be one of them. I do not have any PCs with SATA but here are some ideas that might work.
http://www.linuxmafia.com/faq/Hardware/sata.html