I used to have a Kenwood TK-7180 (also a TK-2180 portable) and absolutely love them!!! Kenwood's in general are easy to program. As said before, newer software versions don't like to work with older firmware. But in some cases, they work just fine together. The TK-x180 series radios are great not only because of the abundance of features that can be programmed into the radio, but they will do either MDC-1200 or FleetSync features as well (but only one or the other, you can't program them to do both at the same time unfortunately).
As far as cables go, Kawamall on eBay is a very good source for the cable. I have purchased several from them, and even directed them towards improvements for the KPG-36 cables to be compatible with all the radios that they program (I got a free one out of that. It was a pin-out problem.. LOL)
Software..... Do beware of where you get it. Some will scam you. There are Kenwood groups on Yahoo that can help you with the more specialized programming questions. I am a member of several, and there are some very resourceful people in those groups.
Please feel free to email me (as I don't get on here enough to answer PM's) if you have any questions about it. As I said, they are awesome radios that are packed full of features!!!!