Depending on your setup and gear you could bond the NICs with etherchannel and make it "2GigE"
Have a look here: http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1004048
and here: http://longwhiteclouds.com/2012/04/10/etherchannel-and-ip-hash-or-load-based-teaming/
However in most cases, load balancing with the default policy is recommended.