Yes, it seems Cubase LE5 is the highest version available for non-Steinberg/Yamaha hardware; I’m guessing whatever deal they struck back then has not been renewed since Yamaha took over Steinberg. A friend bought a Tascam interface recently and it came with a Tascam-branded Cubase LE5 (as in: it say “Made for Tascam” as Cubase loads). It works wonderfully well on Windows 7 (even 64-bit Window 7, as a 32-bit application) and is totally stable and more than adequate for what he wants to do (basic multitrack recording).
Lester: is the problem that you have no software at all with the H4N? On my H1, the software was actually on the SD card fitted in the device itself, if you connect it to a computer it shows up as a card reader and there’s the software ready to be installed. Cubase LE5 allows you to use it fully for 30 days before registering anyway.