No electric expert but you don't need a 5V voltage regulator when you use the 5V from the Arduino it is allready regulated.

You state you use the WIZ5100 library, is it compatible with the WIZ810MJ ?? Have you checked the datasheets?

This module requires 3.3V and yes the module is compatible with the standard ethernet library.

@simp you need to connect the RESET line to a digital output pin with a 10k resistor.  Set the output HIGH for normal operation and you can toggle it to reset the module in code.

It really depends on the application.  I have around 30 Arduinos running in an industrial automation setting without any problems.  A lot more thought and preparation has to go into it, but it makes sense in some applications.  I don't use them on mission critical stuff.  As far as injuring operators, that is always a concern even if you are using a PLC.

On a multi-million dollar machine, an Arduino would not be my first choice 

Check out the TextString library.

http://www.arduino.cc/en/Tutorial/TextString

This looks like a fun project, I'd hate to see you give up.  It may be worth trying the SPI interface for these displays.  It will require 3 pins for the first display and 1 additional pin for each subsequent display, 6 in total (but each display will have 3 wires sharing the MOSI and SCK).  It looks like someone else may have done the ground work on talking to this display over SPI:
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1247533060/2

Check out the string library, should help you do what you need.

http://www.arduino.cc/en/Tutorial/TextString

Goodbye techx, you are welcome!

This thread is starting to remind of a thread from a couple weeks ago where someone started acting rude when the answers were not to their liking.  If techx responds that I am clogging the internet with this post, we will have a winner!   ;D

I would suggest you head over to http://www.avrfreaks.net/ if you are not interested in the Arduino IDE.  Without the bootloader and IDE it is not really an Arduino any more and simply becomes a breakout board for the 168.  As this forum is centered around the Arduino you will find much more information about AVR Studio on the avrfreaks site than you will here.

Your workaround continues to point to other software on your computer that is blocking the serial port.  It could be anti-virus, blue-tooth, or a range of other programs that are causing the conflict.

Maybe you have another program running that is blocking the port.

Check the link for more suggestions.

http://arduino.cc/en/Guide/Troubleshooting

Why does your error message say you are using COM5?

Those files are supposed to be there Pat and I have WinAVR installed on my machine without it causing any problems.

Did you find the programmers.txt file?

Have you tried deleting your entire Arduino folder and downloading a fresh copy?

It would be nice if you were able to try it on a another computer.

I wouldn't give up yet.

Programmers.txt is in Arduino\Hardware\.

Can you try another computer?

Did you also send the RS232 to TTL adapter back for verification?

How do you have the adapter connected to the RBBB?

People may not be responding because this sounds like a problem with your computer rather than the Arduino.

Have you tried another computer?

What is in your programmers.txt file?

What did you change from when you initially started because this is not your original error?  From reading your others posts it seems you may have tweaked something on your computer that is causing your problems.  Maybe your other AVR software is conflicting?  It's hard to debug without know exactly what you did along the way that made your error messages change.

Are you sure about the server IP?  It's dead for me it I try to ping it.