cpu load for 50 simultaneous SIP-to-SIP calls with Digital Recording

Hi friends,

I am new to Asterisk, have installed Trixbox 2.2 with 4 port T1 Digium card here is my system configuration.-
Processors 2
Model Intel(R) Pentium(R) 4 CPU 3.00GHz
CPU Speed 3 GHz
Cache Size 1024 KB
Kernel Version 2.6.9-34.0.1.ELsmp (SMP)
Distro Name CentOS release 4.3 (Final)
Uptime 2 days 1 hours 10 minutes
Current Users 0
Load Averages 1.64 1.33 0.87
Physical Memory 3.47 GB
Disk Swap 760.88 MB

I like to know cpu & memory load for simultaneous 50 SIP-to-SIP calls with Digital Recording. How much mixmonitor function effects the calling if there are simultaneous 50 calls

Thanks in advance.

Regards
Tushar