You are correct about NO Packet in HRD. I also believe the new owners of HRD will also elect not to add it.
You would be better off using the AEA PK-88 for VHF Packet. There are few Windows based programs to use with the TNC. So unless you want to lay out some cash for some of those fancy programs I have a few suggestions. One would be to use a Phone Modem program like Procomm. It will even let you create some Macros/Meta Keys for Connection/Disconnections as well as other options.
There is a Windows based program that has gone the Freeware route and that's called XPware at: http://www.glaswerks.com/xpware
I have use it on both Windows 98se, 2000, XPpro and Windows 7.
Another is NuPacket at: http://www.hotamateurprograms.com/downloads.htm
Simple Windows Packet Controller, Version 1.30, WindowsXP, Windows Vista Compatible, and Windows 7 Compatible.
I also have the Software plus others in the FILES section on my Yahoo User Group at: http://groups.yahoo.com/group/packet-radio
If you have a PC with a Serial Port supporting Standard Base & Interrupt settings and AEA PCPakratt 1 & II program you might be able to use them.
Sorry to hear you bought MixW. Even though it supports Packet it is a little cumbersome to use it on that mode. The program lacks a lot features as compared to what's out there, like HRD/DM780, MultiPSK and FLdigi which are all MultiMode programs and are free. MultiPSK does supports Packet ops.
I am not sure why you would want to Interface AGWPE with DM780.
Regarding the TS-830 it would be OK to start off with BUT a few things you should be aware of.
1. The Receiver needs to be ROCK steady or you could find yourself chasing your Tail all over the Waterfall.
2. There are NO connections on the rear of the Radio to plug in a Sound Card Interface into. DataPorts which are found on the current Radios and also going back as far as the TS-440s in the Kenwood series. This makes it easier to Interface to and also they usually have a RX Audio line that has a Fixed level to it and is not affected by the Volume control and also has both TX Audio, PTT line and Ground. That would be the ideal setup.
3. Connection will have to be made the Mic Jack and Receive Audio either picked up from the Headphone or Rear Ext Speaker Jack. One of the reason to avoid the Mic Jack is TX Audio Levels and the over driving of the ALC which can lead to splattering of your Signal on the Waterfall.
4. Are you planning on a Homebrew Sound Card Interface or a Commercial one. If you plan on using the TS-830 then I would get a Rigblaster that supports a Mic Jack for leaving the Mic connect to the Radio.
They have several different models. If you think you will upgrade the Radio sooner or later then maybe look at the Tigertronics Signalink USB Interface.
73 for now de Steve KB6HOH