SCCM collection for Virtual or Physical computers

Computers that are running on virtual(Virtual PC or VMware etc) will have an entry in win32_computersystem with attribute model in WMI.

You can create a collection to using table called SMS_G_System_COMPUTER_SYSTEM.

select SMS_R_SYSTEM.ResourceID,SMS_R_SYSTEM.ResourceType,SMS_R_SYSTEM.Name,SMS_R_SYSTEM.SMSUniqueIdentifier,
SMS_R_SYSTEM.ResourceDomainORWorkgroup,SMS_R_SYSTEM.Client from SMS_R_System
inner join SMS_G_System_COMPUTER_SYSTEM on
SMS_G_System_COMPUTER_SYSTEM.ResourceId = SMS_R_System.ResourceId
where SMS_G_System_COMPUTER_SYSTEM.Model like "%Virtual%"

To list all physical computers ,create another collection using operator not in from above collection like below:

select SMS_R_System.ResourceId, SMS_R_System.ResourceType, SMS_R_System.Name, SMS_R_System.SMSUniqueIdentifier, SMS_R_System.ResourceDomainORWorkgroup, SMS_R_System.Client from  SMS_R_System where SMS_R_System.ResourceId not in (select SMS_R_SYSTEM.ResourceID from SMS_R_System inner join SMS_G_System_COMPUTER_SYSTEM on SMS_G_System_COMPUTER_SYSTEM.ResourceId = SMS_R_System.ResourceId where SMS_G_System_COMPUTER_SYSTEM.Model like "%Virtual%")

Hope it helps.