I'm not sure that moving to XP home could be called an upgrade. You would be much better off getting a proper operating system - XP Professional would be fine.

LimeWire should work fine with XP. Make sure that you install all the patches for XP before anything else.

Then switch off the built in firewall (or learn how to configure it to allow LimeWire through).

Then get the latest Java from Sun (there's a link on the LimeWire download page and a link gets posted in the forums moderatly regularly) and install it.

Finally, download LimeWire and install it.

This should give you the best chance of getting LimeWire working first time.

Mark