There is currently a bug with vmware server network performance on modern Linux distributions (particularly when performing host->guest and guest->guest data transfers. The following discussion thread has found that it is a kernel bug, and provides a quick fix solution.
http://www.vmware.com/community/thread.jspa?threadID=34497
>>Linux download a useful tool called 'ethtool' and run 'ethtool -K eth0 tso off' where
>>eth0 is whatever network interface u are using.