I remember hearing there was an over internet MIDI thing in the late ninties, can't remember the name of it.

tbh, the simplest solution would be to use one of the many conferencing systems available like skype (although not a great example since it batters your connection with peering), set both setups to the same tempo and audio record the OSes audio i.e. recording Windows Stereo Mix.
If CPU load is an issue, probably best use a seperate system for streaming/recording and link with line out to in, unless you know/or know someone which can do optimal OS/audio system installs.