hardware requirements for audio

["emanuele ..:: www.rumoridifondo.com ::.." <emanuele@xxxxxxxxxxxxxxxxx>]

when i play hexter from rosegarden and with 32note of poliphony i get 
some xrun with jack. the same if i play "The Master" synth in LMMS.

now i got a doubt: what are the raccomended requirements to make audio 
with linux? i got a celeron 1.7ghz and 512 mb ram and i'm using ext3 
filesystem.
with this configuration and windows xp and cubase sx2 i manage to record 
& play with B4 fm7 absynth battery hyper canvas, all open at the same 
time and i don't have problems.

is it possible that with linux and rosegarden and hexter i got xrun 
problems? may they depend from system configuration? i use mandriva's 
kernel multimedia with realtime module....

bye
emanuele