Dual Gigabit MB

I look after a small business network, however I should point out that I employed as an accountant not an IT guy.

We are looking at replacing our existing server with the following running SBS2003.

Processor: INTEL CORE i7 920 2.66GHz 4.8GT QPI 8MB CACHE LGA1366
Motherboard: GIGABYTE GA-EX58-UD5 MB, Intel X58+ICH10R, QPI 6.4GT s, DDR3 2000, PCI-Ex16, SATAII, RAID, IDE, 2xGbE LAN, 8ch audio, 2oc PCB, USB2, Heatpipe.

All workstations have either gigabit MB's or gigabit netowrk cards. I believe most cabling we have is Cat 5.

Any suggestions as to the best gigabit switch to purchase. must be at least 16 port.

Thanks.