IdanAbutbul - keep it simple - explore the capabilities of just using serial ports - look at my posts under "Momentary Switch" earlier today. Having said that I found using my new Ethernet Shield I received last week relatively simple to use out of the box when following the examples in "playground" & connecting through my home router - even was able to get web workingh to my mobile phone.
If you want to advance into GUI look at these postshttp://arduino.cc/forum/index.php/topic,131915.0.html
for discussions on a GUI advancedHMI http://arduino.cc/forum/index.php/topic,131843.0.html
for link to Weeder Technologies froduct that has a published protocol
So much code to explore and so little time......