The 5mx might be behind the times in terms of processor performance and have a B&W screen, but it's a good thing to have a keyboard attached, an rs232 port, IRDA, native compact flash slot, a lot of available peripherals, and the ability (if you install PsiLinux on a CF card and use arlo to boot into it) to dual boot your palmtop.

Note that the Agenda is also still available.