We run our DS in a VM as well. DS 6.9 SP5 MR1, actually. We run it on a VMWare ESXi host, and have defined 2x 1Gb NICs and a virtual switch. We have then teamed the NICs to give us more throughput. The server it's running on has a 10Gb NIC (multiple actually), so it works pretty well.
To be perfectly honest, this system has been more stable after a "Physical-to-Virtual" migration onto ESXi than it ever was on a dedicated HP DL385 server. I recommend it, and it looks to be supported by Symantec as well now.
Best thing is, we can back up the databases in SQL, then snapshot the DS, then try the latest hotfix or SP. Wort case, we restore the databases and roll back the snapshot... and it's like it never happened. You can also clone the VM into a test environment... which is pretty cool.