Your 3635 should work well with the remote extender. I assume you are referring to the PDA-ir CF extender.

I have the same setup (iPaq 3635, TV Remote 5.1, and PDA-ir extender) and it works well for me.

By the way, I agree with westmetro re: PDAWin. I like the software and I use it every day, but it could use some further development. Unfortunately, the company that develops it is unresponsive, and if the look of their website is any indication, unprofessional. Just my opinion, of course.

Regards. Jay.