Just a quick note: all Macintoshes from the Power Mac G3 onwards (G4, G5), came with (minimum) 2 firewire 400 ports......built in. Firewire is Apple's baby. As firewire advanced, newer Macs like the PowerMac G5 came with Firewire 800 and 400.
And, I would like to make clear that I am not affiliated with Apple or any Firewire company. I'm just a big fan of good technologies and firewire is one of them. I also think that USB is a great technology, but it's design is not better suited to the demands of digital audio. The proliferation of USB audio devices, I believe, is mainly due to USB's extreme popularity, like MP3.
With specifics to this thread, the original poster may want to consider getting a used G4 Mac to interface with your Firewire device. VNC would be used to remote control the Mac from your Windows PC.
CD
David
iTunes 7,PowerMac G4 733, Mac OS X 10.4.11, Airport Express, Beresford TC-7520 (Dual LM4562NAs) MLC5/6 clipped, 36K and 100nf cap mod, Behringer EP2000, Cambridge Soundworks Tower II