asterisk users - May 2003 - hardware for 2 external and 12 internal lines (all isdn)

hello all

what hardware do i need to set up an asterisk box with 2 external isdn
lines and 12 isdn phones? will an e100p (i'm in poland, europe ;) plus
a channel bank do? how do i go about connecting all this stuff
together? could you please suggest some cb models (prices)?

how much cpu power/ram/whatever else will i need? will some older pc
(like a p2-400 w/128 mb) provide adequate performance/sound quality?

forgive my lameness, i'm still learning ;)

thanks in advance
  grzegorz nosek