I recently installed Ubuntu Studio on an icore7 desktop with 4GB Ram, two terrabyte hard drives, two nvidia gpus and three monitors.
I've been playing with jack, ardour, hydrogen, rakarrack, virtual key board, qsynth etc.... and have been able to get things working with relatively low latencies using the mobo's onboard sound.
In terms of audio hardware, I've got soundcard onboard the mobo and a pair of akg headphones.
I'd like to purchase enough hardware to enable some decent songwriting and demo production. In terms of soundcard and/or external box I'm looking for a couple of hi-z inputs, a couple of mic inputs, phenomenal a/d d/a conversion and full support for the hardware in linux -- any other ins/outs would come in handy but aren't required a straight digital out and midi would be great. There are a hundred products out there... I'm looking for recomendations.