WinXP does not recognise a second HDD?

I upgraded from Win98 on a 3Gig drive to WinXP and a 120Gig drive. As soon as I hook up the 3gig drive as the slave winXP does not boot? If I change the IDE-0 to IDE-1 then Win98 boots? The HDD jumpers are correct as are the HDD IDE connections. The BIOS recognises the 120 as the master and the 3 as the slave.
So what is the problem?