asterisk users - Oct 2005 - VoiceGateway Design - Request for comments/suggestions

Hello Group,

I'd like to hear your thoughts for the following design. To implement
a Voice Gateway solution with atleast 2 PRI (60 channel) capacity, is
it better to implement
- 1 Grunty Server with a BiPRI card (TE205P, 210P) / Quad PRI (TE405P, TE410P)
or
- 2 Normal Servers (Dell 420/430 with 2 Gig RAM and 80 Gig SATA) with
Single PRI (TE110P) or BiPRI (TE205P, 210P) and Load balance between them.

My second question in similar lines is, is it better to implement
- 2 single slot ISDN Card
or
- 1 multiple slot ISDN Card.

While option 1 gives us card level redundancy, option 2 only gives us
slot level redundancy. With regards to responsivenes/performance
(memory usage et al) is option 1 costlier?

Has anyone experienced malfunctioning of some slots an ISDN Card, but
other slots in the same card functioning normally?

Thanks for sharing your thoughts.
-r