Although I still think a Limewire timer is a good idea I did get the Win XP one to work. The previous problem had to do with not being logged onto the machine, but I worked that out.

start/programs/accessories/system tools/scheduled tasks

and then you enter in that you want Limewire to run each night from middnight, or 11:59pm if you are like me and perennially unsure if midnight is am or pm.

You can even tell it to run for a certain time under advanced options, ie 7 hours if you are on a mid-7am off peak rate.

happy times