Depends on your needs. If a general file/print server, you could use link aggregation for more bandwidth. That team will allow ports to fail and still maintain the connection and IP addresses until only one port is left.
I've never had more that 2x GigE. At that point, I just don't have storage arrays fast enough to keep up with the network speed. Even at a fast 120MB/sec transfer between two servers with RAID arrays, that's a tick less than 1Gbps over the network.