SCCM Global Condition for PC System Type (aka Application "Requirement")
Name: PC System Type
Description: Possible values: 1 (Desktop), 2 (Mobile), 3 (Workstation), 4 (Enterprise Server), 5 (SOHO Server), 6 (Appliance PC), 7 (Performance Server), 8 (Maximum), 0 (Unknown)
Device Type: Windows
Condition Type: Setting
Setting Type: WQL Query
Data Type: String
P.P.S. Bonus: Use WMI Explorer 2 to browse WMI and find thousands of ways you can rinse and repeat these instructions for different purposes. The ScriptingGuys have a great article on WMI Explorer and you can download it here.