I just picked up a 501 yesterday - my HT is downstairs, music upstairs and I kept forgetting where the remote was!

Daveds The software (Freedom Editor) is a modified version of NeoEdit. It will open (and translate) a 500 .ncf file and download to the 501 successfully. Note that NeoEdit will NOT open a 501 file - so I don't think Neoedit will work for you. Let me know if you want a copy of the software - maybe I can upload it here.

When opening a 500 .ncf in Freedom Edit it says "you will lose some features" - as far as I can tell using my existing (VERY customised) ncf files this means only that any codes you have on the "f" key (Bottom right on 500) will not translate - there is no key to directly map to this key on the 501. All else comes across and downloads fine (custom bitmaps etc. etc.)

For those interested there are good and bad things about this unit Vs the 500

Good
- the 4 hard keys directly under the screen are real keys - not the fiddly bits of plastic.
- at the top of the screen there are two additional keys that can be programmed
- the unit turns on when picked up
- there is an additional emitter that means you can hold the unit vertically when controlling - this is useful for me as I have 300 CDs coded into my unit and it means people can easily select the CD they want (hold unit vertical to read, press...)
- includes RF control although I don't use this.
- bigger memory (2 Mb). Again, I haven't explored this
- as indicated you can use existing ncf files
- transmit distance seems longer

Bad
- with the exception of the central "wheel" all the buttons are the exact same size; this means that it's easy to hit "Mute" instead of Vol up/down
- it's bigger, slightly longer and wider so a little more cumbersome to use.
- contrast seems slightly less "fine tunable" than the 500

Bottom Line: it is great for me but I'm keeping the 501 in the HT