I use with a roland vm 3100 pro digital mixer. In xp is very easy to use...only driver install and the sound is ok. But with the windows 7 is no sound :(
XP it is then..
Or as John Sweeney pointed out the PreSonus R-bus to Firewire interface may sort you out.
The RPC-1 card might have to 'retire gracefully', or if you are anything like me end up in older machine used for less important duties.
The PreSonus interface is quite reasonably priced, but if you PC hasn't a firewire port, then obliviously you'll need a firewire card in your PC too. These are fairly cheap.