In order for this trick to work you will need to have Admin rights to the machine.  Assuming that this is the case you can then proceed first of all you will want to psexec to the machine then from there simply run a reg query.  The following line of code is what you will want to put in:

C:\reg query HKLM\SYSTEM\CurrentControlSet\Control\SystemInformation\

The results will be likely similar to the following:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SystemInformation
    BIOSVersion    REG_SZ    080112
    BIOSReleaseDate    REG_SZ    06/09/2009
    SystemManufacturer    REG_SZ    Microsoft Corporation
    SystemProductName    REG_SZ    Virtual Machine
    InformationSource    REG_DWORD    0×0