A flash is a flash. If you're using it off-camera, and can live with manually adjusting your power, then the only reason to get a 580EX II over a (much) cheaper flash is the power (guide number). With todays cameras shooting at ISO 200 with very little noise, the extra flash power isn't as necessary as it once was (in my opinion).


As far as triggering the flash, your budget will be the deciding factor in what range your triggers will have and how reliably they trigger.


On the low end, I'd suggest the CTR-301 or the CTR-301p. They're relatively cheap, and don't require any extra wires because the flash simply slides into the trigger's hotshoe. I think the added PC sync port of the CTR-301p would be relatively useless to you at this stage, however, they're a slightly newer product and may be slightly better made than the original CTR-301 (I don't know, though). If you buy a set of these, you'll need to choose an umbrella swivel carefully because you'll want one with a threaded (1/4" if I remember) stud instead of a shoe connector.


For a good middle-of-the-road option, you can't beat CyberSyncs. The products you'd need are the CST (transmitter) and the CSRB (receiver) units. They're made by Paul C. Bluff (of Alien Bees/White Lightning) in Nashville, TN. They're basically as reliable as PocketWizards, but don't have the same range (400-600' instead of the 1600' range of PocketWizards). If you need substantially more range than the length of a football field, then you need the PocketWizards. And if you need the PocketWizards, then you probably don't have any issues paying for them. You'll need a way to connect the receivers to the flash. The best option is to buy a hotshoe adapter from FlashZebra (with the CyberSyncs, I'd personally suggest item #0128).


And on the high end, as you know, PocketWizards. I'm not even going to go on about them because I think they're economically unreasonable for anyone who doesn't make a living doing photography. They are fantastic, but the price is steep.


And if you want to learn more about off-camera flash, check out the Strobist blog and specifically Lighting 101. They are invaluable resources. The blogger, David Hobby, recommends using PocketWizards because of their reliability. However, for most of us, one of the cheaper options above will do just fine.