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You need a PLC configured with the right I/O (relay in/out, analog in/out) with Ethernet and a common, open protocol like ModbusTCP... Automation Direct is a good supplier of these.
Alternatively one could use "dumber" remote I/O devices like these

++mod

I agree and would like to add that when you say "likeley not Ethernet" also means that there are some that are. We've recently started using Directlogic PLC's. Some do have ethernet (like the DL205).
http://support.automationdirect.com/docs/plc_selection_considerations.html

You could run all of your PLC's through a router so you could have all your PLC's programmable from a remote location. We've never done that, but then again we also don't have a prison population and access controls to deal with.

These days, you simply can't buy the serial-based stuff any more... everything has ethernet

i have to call bullshit on this one - i have several clients in the water treatment business and all their monitoring and control systems use rs-232 ports to communicate. automation direct has a huge selection of rs-232 capable plc's, sensors, etc. additionally, ordering a laptop with a serial port is trivial. and why would any of these plants prefer using a serial port over an ethernet port? because the ability to connect (accidentally or not) an ethernet-based control system to the internet is too easy. which, for obvious reasons, is probably something most water treatment plants would want to avoid.....

Consumer-grade crap is crap and it'll fail.

Get a real automation system and wire your house up properly. Hell, with what you're spending on your phone "solution", you could easily get some PLC controls and wire up your house so that it will last for the life of your house.

Here's some less-expensive stuff, but still of very good quality:
http://web4.automationdirect.com/adc/Home/Home

Of course, I'm just an EE that works in automation and control. What do I know?

Which is why he bought a used laptop, it had serial ports but only could run Windows 2000.

The Windows Vista laptop had that USB to serial adapter and it was limited to 9600 baud for some reason. He needs it a lot faster than that, and sometimes it doesn't work right either.

There are projects to get PLCs to work on Linux but some software like Directsoft only exists for Windows XP and 2000 and not Vista or Linux.

Even an embedded Linux platform (e.g. Gumstix) would be a bad idea for this project, as cross-compiling is a PITA. For rapid development (something I have much experience in), go with a standard PC with your development system of choice: C/C++, LabVIEW (really, not flamebait :) , MATLAB, etc.. Basically whatever you already know. Whatever can get data in and out of an ethernet port.

As for hardware, there are so many ways to go. If you have some cash laying around, go with National Instruments as their hardware line is well supported, has a very nice C/C++ API library, and will stand up to the elements pretty well. Even if you're on a budget, they sell some multifunction USB DAQs for less than $200. Buy your motor controllers and control wiring from Automation Direct they'll have almost everything you need.

http://www.automationdirect.com/ is one good supplier. This kind of industrial grade hardware is expensive, so eBay might be the best choice. What you want is commonly called a "mushroom head emergency stop pushbutton". If using it for a PC reset switch, you want normally open contacts, whereas most E-stop systems would use normally closed.

Because of the high prices of duplicators, and the fact that I would have liked to be able to just feed the machine a bunch of blank disks and a couple of spindles of used disks, with different instructions for each disk to be copied, I came up with an interesting plan. I'd post a link if I could handle the slashdot effect, but you might be able to find something similar.

Basically, the idea was to use a 4'x8' table, a mini-ITX case with a bunch of external drives (some readers, some burners, depending on your needs) and an Automation Direct PLC with serial communication capability to set up a "pick and place" type system that could easily be scripted. I lost my motivation before I had the $2k it probably would have taken me to do it, but the plan was pretty solid.

I think the motivation behind it was an interesting ice cream vending machine I saw, which was more or less a box containing a consumer freezer, an arm to open the freezer, and a vacuum hose that would go to the proper coordinates, drop down, suck up the treat, and drop it into a chute.

Just think of the possibilities though. Thousands of blanks, matched with thousands of sources. It'd make a nifty interface for archival and automated backups, etc.

I have written several conveyor control projects with them- you can do serial port interface using a couple different PLC protocols. Unlike building your own, they come pre-wired with manly relays for both AC (for line voltage) and DC (for motors, etc) contacts and relays (input switches and output for motors, etc).

Programming isn't really hard if you have had an electric primer- you can do simple on/off or write really complicated logic using "virtual" interlocking relays, etc.

If you have the money and some time, a PLC will produce a much better project IMHO than hacking together circuit boards and optoisolators, etc.

This guy is also the supplier of touchscreens to Automation Direct. Sorry, no direct link, Look under Operator Interfaces-->industrial monitors. (Warning, very "busy" site with lots of frames and redirection)