As long as VM Ware is emulating one of the Operating Systems that is officially supported for FileMaker Server 10, and as long as the allocated system resources for the VM Ware OS meets our minimum (but preferrably Suggested) System Requirements you should not have any issues.
After a search of our knowledge base (found at: link) I did not find any related KB's that noted specific issues with VM Ware. The only semi-relevant KB I found was about Using FileMaker software on a computer running Virtual Environment software: link
I hope this helps, and if you have any further questions, please don't hesitate to post them :)
Many thanks for the prompt reponse. I'll give it a go.