Ok I'm making some progress. I think these are the soundcards I've narrowed it down to:
That's the RME Multiface II, the RME Hammerfall DSP9632 and the E-MU 1616. The latter 2 are significantly cheaper, though I'd have to buy a mixer to allow recording of live instruments too. The question is now: is it worth spending that extra money on the Multiface in order to keep latency and other performance issues to an absolute minimum? I'm having a hard time getting an idea of what the difference will actually be.
If there'll be no significant difference, I'll probably get one of the cheaper options with a basic mixer, and spend the money I save on more VST instruments.
I'm so close, bear with me.....