Hello Charlie Hodge, welcome to Geeks To Go,
A fresh install of Windows XP with Service Pack 2 takes up about 2.0GB of harddrive space. I would recommend that you buy a bigger harddrive. Here is a link
to a good size harddrive with a nice pricetag.
Now with the problem with have two Windows XP installilations, is that some ran the Windows XP setup, after already have the first install complete. They didnt finish the installilation of the second install, just copied the files to the harddrive.
Now I would buy the harddrive that I have the link for, making that the primary harddrive and the next biggest one the slave drive. To fix this, I would just do a fresh install of Windows.
To get the registration key, you can look for it in the registry, or you can download this program
, run it and then wirte down the key. If you dont know what you are doing in the registry then download the program. Hope that this helps.