Almost, unless I am mistaken you have missed single quotes either side of the comma i.e.
$wmiObject.GetValue(0)["SystemName"] + "','" + $wmiObject.GetValue(0)["DeviceID"]+ "')"
I am sure that you will have come across the need for quotes within quotes before. Lovely. 😉
Gaz
-- Stop your grinnin' and drop your linen...they're everywhere!!!