General question about 1GB vs 10GB NIC's

[Lee Brown]

I want to build a router that has 2 x 500mb/s radio ISP facing, 2 x
500mb/s radio's facing another site, plus a 1gb/s link to the LAN.

I plan to plug everything into a switch so I can have redundant routers.

So my question is should I go with 5 x 1GB NIC's or 2x10GB NIC's on
the motherboard.  Assume NIC's will be Intel or IBM.  Going 10GB
pushes the switch price ten-times, so I'd like to avoid that if
possible.

I'm planning to get a 4 core Xeon @3.4GHz and it would be nice to know
if this is a moot point or not.

Thanks -- lee