Pretty much the same as you did before, except this time you don't have to be careful how you do it. Go thru the normal reinstall procedure for Windows XP. When you get to the step about where to install it, I would delete the partition and recreate it. This also gives you a chance to delete any recovery partition if you want. As you have an XP SP3 installation disc with all the updates as of a week or so ago, I would install windows, then install your security programs, then update windows and your security programs. Then install all your software. Create an image of the disk as you did on the other machine, then restore your personal data.
The entire procedure is much the same as what it was with windows 7, except with XP it takes a little longer, and there are more questions to answer.