[Users] recomended setup to handle more calls and best performance.

Hi Iam looking some suggestion here after reading some thread some time back people are recomending to use rtpproxy in other PC to achive more calls P4d with 2GB ram, IDE 160GB, 3 Gigabit Ethernet ( only openser) Xeon with 2GB RAM, SCCI hdd / 2 Giga Ethernet ( mysql, radius,cdrtools, frontend /asterisk for voice mail and b2bua) P4 with 2GB RAM IDE 16GB/ 2 Gigabit Ethernet ( only for rtpproxy) openser server connected with other server with cross cable. one ethernet is connected to internet with this setup can i able to achive 1000cals per second. what is the recomendations here. any suggestions ram