use a virtual midi cable like LoopBe Will that still work on Windows 7/8 x64? The last one I tried (which I think was on Vista x64 at the time) was MIDI Yoke, which hasn't been updated since 2007, and I think it caused instability at the time.
MIDI Yoke works under win7 x64 (8??) when using 32bit version of Cubase, but not 64 bit. However LoopBe1 works fine with 64.