Ok. No response as yet but I did a search on "Linux and X10" (Which I should have done first really...)
Anyone else who wants to use Linux to control X10 could do worse than looking here:
http://www.yolinux.com/TUTORIALS/Lin...etworking.html
Here's also a page about Windows software
http://home-automation.org/software/windows_and_dos/
Only problem is that some of the stuff that was freeware when this was written is now Shareware or Commercial. TypicalI might browse what's available and then ask about specific products here.
I still need my hardware questions resolved before I shell out any money on hardware though. All answers appreciated!