asterisk users - Oct 2004 - PSTN -> PRI -> ASTERISK -> ASTERISK -> PRI -> Legacy switch ?

Hello,

  I'm new to Asterisk,  I'll be freeing up some hardware to play with it
next week.   Would it be possible to eat up 3 PRIs coming from the 
phone company (Lucent 5ESS) into one Asterisk box, ship the traffic 
over IP to another Asterisk box and back out as a PRI to a legacy 
switch?  The legacy switch needs to think it is talking to a 
Lucent/Nortel PRI (NI-1, NI-2) as a 'client'.   Would the ANI 
information coming in from the Original PRIs get sent out the legacy 
PRIs?  Essentially, I have a legacy switch that I *cannot* replace but 
I want to put Asterisk in front of it to handle VoIP, IVR, VoiceMail 
....  The two Asterisk boxes will be separated by two PtP T1s (MLPPP), 
3 mbps, Cisco 2620XM series routers.

What type of CPU do I need to handle 3 PRIs + IVR + Voicemail + 30 VoIP 
phones (Cisco 7900 series)?

-Matt