I don't know if You have this or not, But do You have the powertoys for windows xp?
If You don't It may help as Your drive may just be hidden or It's unformatted and needs to be formatted by the XP setup CD possibly. I hope one of these two ideas help.
I have windows xp professional, I don't know what powertoys is, although I look it up, and it seem like its just add-ons. I can format it in windows xp but that would install windows xp into my secondary drive which I don't want to do, which would make me have two dual boots operating systems.

That's strange that it doesn't show up under Disk Management. When I installed my 3rd SATA (first two were in RAID), that's how I had to format it/show it. But it does show up in the BIOS? How about under Disk Drives in the Device Manager?
It shows up in Bios and it also shows up when I do windows installation, when I pop in my windows xp cd. It doesn't show up in Disk Drives in Device Managers, it doesn't show up at all when I load up windows.

If I recall correctly...I had the same issue...
With my circumstance , I had to set the Jmicron raid to normal mode to get the ide drive recognized in windows despite being recognized in bios .Did ya remember to install the raid drvers for both controllers with F6 method a windows install ?
I install Jmicron but immediately disable it and didn't completely install it all the way. I didn't install the raid drivers for both controllers with the F6 method using windows install. Can you explain more? This might be my problem...

Also the hanging problem while multitasking with several programs open, until I close several programs will it go away, does anyone have this problem??