|Why do you need two windows operating systems on the one PC?|
Lots of people do dualboot. If you want to then I suggest you save any data from the second drive that you need, and then format it and instal a fresh operating system on it while it is in the slave position. XP will configure the dualboot during the instal process.
This is not the only solution but is my recommendation.
I used to have a signature but it disappeared and I just couldn't be bothered writing another so please feel free to ingore this.