Optiplex Gx150 only sees hard drives in a certain order

Ok so my friend has got this Dell Optiplex Gx150. I am trying to put a 40gb hard drive in it and install windows, but it only see's the 40gb hard drive when it is on slave and when the original 20gb drive is on master. Both drives jumpers are set to cable select. I also tried the 40gb drive on the jumper setting master, and still not recognized. I know both drives work fine, I tried them in another computer. When I try to just only have the 40gb drive plugged in, the drive isn't recognized in the bios. I tried the 40gb drive on the ide connector with the cd-rom and the bios still wouldn't see it. I am trying to set it up where Windows XP is on the 40gb drive(master) and the 20gb drive is just a spare(slave). The only thing I can think of to try now is a bios update. Anyone got any ideas?