Ok, I don't understand what you mean about the pc speaker... You can't possibly mean that you want to play your midis through a pc speaker!?
As for question nr 2, my answer is "Oops, you asked me something I didn't think of". I have been getting that error message some times when I've been running games with incorrect drivers (mostly outdated roland mt-32 drivers), but I don't think I've ran into them with Ravi's drivers... My suggestion is that you look up Ravi's page (from which you got the driver) and check around because it MIGHT be possible that I gave you a link to the wrong driver (though I'm quite sure I didn't). I guess I'm out of advices now, better send Ravi himself an e-mail because he KNOWS what he's talking about and I'm sure he can help you. I only know that I actually got my midis to work some way a couple of months ago. In other words, it SHOULD be working. Question is how... Good luck now, buddy!