Dual Boot SATA and PATA?

[The Wassermans]

I currently have Ubuntu 8.04 loaded on a SATA and dual boots with
Windows XP.

Because I needed a clean install of XP, I decided to take the
opportunity to install XP on a spare PATA drive,  Fully expecting to be
able to simply redirect the dual boot instruction to fire up XP on the
PATA drive in the same way as it did previously.

At present I can only access the XP when I want to by changing the Boot
priority in the BIOS each time.  It works but I don't like it.

I need some guidance please.

Dave W