I would not recommend the 580EX for you because you said budget is a factor. I have a 420EX and a 350D and I am completely satisfied with the combo. The 430EX is better than the 420EX. The 430EX has plenty of power for most situations and it has a bounce and swivel head (I recommend bouncing your flash instead of shooting straight on whenever possible). Heck, if you can find a used 420EX you could buy that and save even more money. Sure the 580EX is more powerful, but it costs significantly more. If in the future you decide to try a multiple flash setup with a master and a slave, you can then buy the 580EX and use it as the master and the 430EX as a wireless slave.