I have two servers runing SuSE 9.3 64 bit. They are on a Gb ethernet switch. Both of them have Gb cards (integrated. One is a Supermicro board, the other a Dell). dmesg on both of them shows:

eth0: Link is up at 1000 Mbps, full duplex

So when I do a file copy (ftp, rsync) I only get 5 to 11 Mbps transfer speed. Right now my copies (one at a time) are the only thing happening on either box.

Do you have a suggestion as to where else to look for the slowdown? What else can I check that will give me a better idea of where the slowdown is occuring?

Thanks!

That does seem slow for 1000BaseT, right on for 100BaseT. I would check to see how much data you can transfer to and from you disks locally. Try copy the file locally with cp,scp and ftp. If those transfer rates are slow too it is probably your disk that is the bottleneck.
If time seem good use ifconfig to check for errors on the network cards and use ethtool on each machine to confirm the cards have negotiated with the switch correctly(note that mii-tools does not support 1000Bt). I know in dmesg that it shows 1000 duplex, but it cannot hurt to check again after the machine has fully booted.
As a final note I would run vmstat on both machines while the file transfer is being to see what the machine is doing with memory/swap/cpu and disk during the transfer. You slow performance might have nothing to do with the network.
Good Luck.

If you're copying files between hard disks over a network, then you won't get anywhere near 1Gb transfer speeds. I get about a maximum of 5 MB/s using Samba.