Not to overhype the iPad solution, because I hear you about relying on a multi-use software solution (meaning the iPad isn’t just for music making). To leave the computer out, I would recommend getting an iConnectMidi 4+ (or 2+) to handle the MIDI end of things. You can connect that to your iPad (though I’m not sure it can be used with iPad 1). I’ve not tried it yet, but it could be an option.

And since jitter is an issue with any software solution, you could also throw in the Acme-4 in to the mix. Although not cheap, it’s suppose to be rock solid! SND ACME-4 Advanced Clock Management Engine