Then edit out the line pointing to the version of XP that you are going to delete.
http://support.microsoft.com/kb/289022 is a very good start.
I have a new build PC with 3 SATA drives. I initially installed Vista 64 on the largest drive, XP on a smaller one, and used the third just for data files. I made a mess of the dual boot set up initially by installing XP second, but eventually got that sorted.
Then I decided that Vista was not for me so I tried to reformat and install XP on the larger drive. I now know that was the wrong way to do it because that failed and I couldn't get rid of the dual booting into the, by then, non existent Vista. Thanks to advice from these forums, I have now sorted that too and successfully installed a new version of XP on the larger disk.
So now I have 2 XP installations, one old, one new, with dual booting. I want to remove the old one and eliminate the dual booting, but given the problems I have had so far I am very wary about just blundering in and erasing the contents of the old disk, then reformatting it.
Any advice on a trouble free way of doing this would be much appreciated,