You'll find that your hanging up problems will go away by upgrading to the intel-based macbook pro. They are way faster than the G4-based machines, and therefore handle Java-based apps like Oanda's platform with no sweat at all.
ja, new macs are much faster than they predecessors ....g3/g4 suck too much cpu hinderin' your tradin'. go for dual core and u'll be happy....and uh, oh, yeah...fuck windows...cheap shit for the masses