I just acquired a couple of MX-700's and managed to download a copy of the MX Editor software. I seemed to figure it out o.k.

Unfortunately all the computers I have (5!) none of them have serial connectors. The supplied cable with the MX's are serial. I happened to have USB to serial adapters, which auto installed the drivers no problem in Vista. Problem is when I use the adapter cable with the supplied MX cable I get port errors and it won't download. I confirmed the port numbers in Vista and matched the config in MX Editor and it still doesn't work.

Any Ideas?

I don't think most usb to serial adaptors work well. The only one that seems to work reliably is the Keyspan model USA-19HS.

A cheaper solution might be a header cable. While most new computers dont' have serial connectors, they usually have the serial port header on the motherboard. You just need to get the adaptor. It is usually an slot cover with a serial port on it and a ribber cable that plugs into the header. Here is an example:
[Link: cgi.ebay.com]

Either Belkin or Keyspan will work. Also, I've heard of people having good results with the current Radio Shack one as well. Do a search in the URC Consumer forum as there are a number of threads there on this subject.

Mike