Hi.

I think Cygwin is a good idea. It will require installation, however.

A Google search for "free shell account unix OR linux OR bsd" yields about 1 M hits. Then all you'd need is telnet or ssh on the XP box to get to the shell account.

Further searching for training materials of the level you wish, could result in a self-teaching, self-administering course and environment for your friend with you as backup for tough questions.

Best wishes ... cheers, drl