[ic] browser detection

[Interchange User]

i currently have 132 categories and 19 areas in my store

the category_vertical navigation code was several screenfuls long on the
left side

so, i use a javascript cascading menu, it displays fine on mac-netscape,
windows-ie/netscape

it will not display on mac-aol, mac-ie4
(not my choice to support these, i have to)
how can i detect browser info with interchange and send back:
   my javascript body if not Mac
   the standard category_vertical stuff if Mac

thanks

Jon