Which flash

I have a 40d and looking to add a flash to my meagre setup. What is the difference between the following flashes 220 ex, 430 ex and 430 ex II. The 580 is out of my price range.

I am a complete novice with anything other than a pop up flash. I am looking for something to get started with and act as a slave if I require it at a later stage.

Can anyone recomend a lead so I can use it off camera.

Thanks

http://photonotes.org/​articles/eos-flash/#faq1

http://photonotes.org …0exii&flash3=ca​non580exii

I'm on a similar page as you are
Allow me to direct to you to these two very informational pages
Good luck

Thanks for the very prompt reply, they both look very comprehensive. Unfortunately work calls so I will have to the first link when I get back.

Regards