Well, it certainly can be done. But, you are going to need to do a lot of reading, and get into some nuts and bolts of the software end of it. I'll do as brief of a description as I can. This is assuming you are wanting to do a full time APRS station, digipeater and Igate, and have a full time internet connection available.
What you need:
A decent Windows XP machine.
UI-View32 APRS client software
Good, stable radio (such as a modern 2M rig, or even a Motorola GM300)
First, the computer needs it's BIOS set to "restart on power fail". That way it will stay running as long as power is available, and restart after a power failure. If you have generator power as automatic backup, that's even better.
The UI-View32 software has to undergo a lot of modifications. A lot of the changes that have to be made are detailed at this website (http://www.wa8lmf.net/aprs/UIview_Notes.htm
). Also, the ini file has to editied for the digipeater to work right. (DO NOT SKIP THIS!) This page (http://www.apritch.myby.co.uk/uiview_newn-n.htm
) will detail what has to be changed, and even has a form that generates the changed text so you can copy and paste it. You also want a shortcut to the UI-View32 exe in the StartUp folder so that it automatically starts when the repeater does.
The IGate has to be setup (if you plan to do that), and I set the UI-View32 Scheduler to automatically connect to the internet one minute after the software starts. It is also a good idea to set the Scheduler to do a RESTART of UI-View32 once every 24 hours. That does a memory dump in Windoze. (UI-View32 will usually, not always, stop responding about every 3 days without the RESTART.)
The TNC you use will have to be capable of KISS mode. Documentation on both those TNCs is available on the Internet, if you don't have manuals. I'm not sure about the 2400, but almost positive the Plus will do KISS. Either way, I would have a battery backup that has no change over for the rig and TNC. Kantronics TNCs can do some weird stuff when power fails for even a second. If you want a good choice for what you are wanting to do at a fair price, but better, look at the TNC-X. you will need only the TNC, no daughter boards, and the USB option if desired. (http://tnc-x.com/
The rig has to be stable on frequency. (Voice of experience here...) Our club's first rig wound up drifting about 6khz off frequency, and you couldn't get it to stay stable. (Old KDK.)
If this is going to be at a remote location, such as a club shack in an EOC or something, you can do several things to "monitor" it. One, have at least a listen only APRS setup at home (scanner, sound card, AGWPE, UI-View32). You can also check http://aprs.fi/
occasionally to see if it is up. (Most of the time, you can enter the call sign in Google and one of the links will be to that website.) To actually be able to control the computer remotely, you can use the free version of LogMeIn.
I hope this helps you some. Like I said, it's going to be a learning experience. Make sure to talk to other APRS sysops around you, as you do not want to do something that breaks the system. A mis-configured digipeater or IGate can wreak havoc in a local area, and even to the entire system.
I am sysop for KG4FZR-7, the McMinn Co Amateur Radio Club APRS Station, digi and Igate. It's up almost 24/7, and is pretty much as described above. (Plus a packet system, including digi, node, and WL2K RMS... see http://www.mcminnarc.com/kg4fzrdigital/kg4fzrdigitalops.html