Hi,
just install your Home Edition on C:
If you have to format first just follow the XP Install dialog, it will ask you what to format and where to install XP.
Afterwords just use a pationer programm such as Powerquest Partition Magic,or "Hard disc low level format tool"(free) and sreate an additional partition at the end of your disk.
In the size of quite your XP install directory (C:), and get some Backup Software, such as "DFIncBackup Professional" or s.t.else to create a backup of your operatio system inc. all installed programmes and all folders (compl. drive C:), to just backup (copy back) the last working state of your system back to C:, and nevermore have to reinstall all your programms ans Windows.
If some trial software expires (after 30 days or so), yust un-and reinstall the expired prog.(but keep the Backup image, and use it for the next 30 days.
Maybe you visit some "Serials" websides or check "www.gamescopyworcomld.com" for some links leading to "Serial" offering sites.
Good luck and have fun...............
Thomas