The only PDA that seems to use consumer wavelength ir diodes is the Dell Axim, the X3 and X30 give excellent range (I think the X30 has less range though).
I'm happily using NetRemote (incl. working repeating buttons!) and found the X3 giving me a 5-7m range whilst being a bargain...
Try it- it's downloadable from proximis.com.
Most HP's (Compaq) have a very limited range, dunno abt others.
Of course you'd best construct your own ccf file, it's a lot of fun, but that's a different story!
Barend