I have a stripped down version of XP, as an ISO, which I want to put on a netbook (which has no CD/DVD Drive)

I need to create a bootable USB so I can do this.

All of the online solutions seem to require a Windows machine to do this, but I only have a Mac.

Any suggestions?

Virtualbox, then install XP and set it up that way following guides online...

http://www.virtualbox.org/wiki/Downloads