okay. Basically you need to open up your case and put this harddrive into it. Firstly, make sure that the jumper setting on the side with all the connections iset to Slave. There should be a diagram on the harddrive that shows you which position is slave.
Now connect it all up properly (you cant really stuff this up), and turn on your comp. Now in windows XP, go into control panel/admin tools/comp management and then under Storage click on disk management. the new drive should be there (under a new letter) Right click it and FORMAT it.
WHen finished, transfer any files you want onto it. Tun off ur puter, take out the harddrive and put it in the other comp. Do it the same way (accept dont format this time) then transfer all the files off
. Much quicker than a network, but a bit more trouble