Compare Microsoft SQL server performance between virtual and dedicated server
Testing isolated queries isn't going to help you make this decision. As you have an existing database live, use it to capture a  representative workload.


Capture a profiler trace from your live, dedicated server
Use the RML toolset to create a replay file
Execute against the virtual server using ORCA


I posted a brief summary of the RML tools in an earlier question which you may find useful. To compare results across both runs, capture a trace of the first trace being run against the virtual server and run both through ClearTrace.