Hi,
I use one of the new PowerBooks, which have S/P-Dif in/out. It is equipped with 2GB Ram. Midi comes in via the MT4.
As borg said, the Built-In audio is very reliable and I can get down to 64 Samples (1,5 ms) without problems.
As software I use Rax and the AU version of the EXSP24 or Ivory (with a firewire drive) for piano playing and Live for clubmusic.
Quite funny browsing the forum, doing mail, etc. at the same time. I'd never do this on a wintel machine

If I go live, I use the analog out, which has now a 24bit converter. Very small setup and very few stuff to carry around.
Network: Tiger has midi over network capabilities, but of course this works only from mac to mac. The same is true for audio, where you have a netreceive and netsend AU, which can be used in any AU capable host. There's some latency, so with a direkt audio connection (analog or digital) it's still better.
There's also an aggregate device now, where you can combine several audio cards (incl. the build in) to one.
All document files from the pc can be opened on the mac, if there's an equivalent of the file creating software on the mac. For the apps you use, you'll need a mac version of course. I can even open the logic 7.1 mac files with the logic 5.5.1 pc version.
Of course, If you want to have a lot of Ram and a hell of performance, get a G5 and stick additional 4GB in it.
The G5 2GHz DP has roughly 5 times more power than my PIV 2GHz - both running logic (can't tell for other apps).
I wouldn't use a miniMac for audio stuff, as it is very limited and doesn't deliver enough power on the long run. It's good for office stuff though ..
cheers
Wolfgang
<font size=-1>[ This Message was edited by: wolf on 2005-05-06 10:18 ]</font>