A standard FC card from the vendor (HP) should work, or any they certify.
The Apple card has Apple-proprietary firmware on it and it is no surprise at all that it won't work in a standard PC.
The Apple RAID at this point is probably getting on in age, you should think about that fact - probably want to fully rebuild any RAID volumes and run the other checks available.
The last version of RAID admin was 1.5.1 as far as I know, which is available here,
http://support.apple.com/downloads/Xserve_RAID_Admin_Tools_1_5_1DO note that they provide a .zip downloadable version. It's a Java app, and with Java installed
it runs perfectly fine in XP SP3.