1 nic per server if at all possible!!
A – multihomed servers are for systems limited by resources. The server has to be the gateway & firewall & web server & so forth. NOT an optimum choice.
B – even with virtualization multiple servers/applications are quite happy to share the NIC. 1 Gigabit nic always beats 2 100mb cards.
C – Multihomed server develope strange problems as Windows, being helpful, adapts routing.