Glenn,
AFAIK, C$ is interpreted as C$, and not as a variable, even when the option "NoVarsInStrings" is "Off". The difference is the $ at the end.
Code:
Break On
Dim $RC
$RC = Dir("\\"+@WKSTA+"\C$\*")
While $RC <> "" AND @ERROR = 0
	? $RC
	$RC = Dir()
Loop

But I also prefer to set "NoVarsInStrings" to "On".