Is there another way to check is a font is installed other than checking if file exists in font directory?
Like Hilmar said, AFONT() works a treat. My public application object has a property called "MonoFont" that is assigned once up-front in the initialisation process with the following code:

private x
if afont(x)
    THIS.MonoFont = "Consolas"
    if ascan(x,"Consolas") = 0
        THIS.MonoFont = "Lucida Console"
        if ascan(x,"Lucida Console") = 0
            THIS.MonoFont = "Courier New"
        endif
    endif
else
    THIS.MonoFont = "Courier New"
endif

When I have controls that need to be fixed-width, I just set their .FontName = goApp.MonoFont.

- Colin