Vorvis brings up a good point, and one I would like to elaborate on.
Buying at the big-box superstores is very tempting, especially if you have a budget. I'm going to suggest you don't do that.
Find a good camera store that sells video stuff and have the sales staff work you through the models features, controls, etc. Explain to them that you have a Mac for Digital Video and want quality results. You may pay a little more (or you may not, these days prices are competitive everywhere) but the support you get will definitely save you some money and grief (when comparing prices, I add $100/hour to a product's price for grief, cuz I hate that job).
A lot of people will select models at a store like that and then run out and buy the cheapest model elsewhere. If you are absolutely broke you can too, but these places know this happens; purchase and cultivate a good relationship (buy tape, etc) with them and the deals will follow. You get the best of both worlds.
I shop at a camera store where they actually lend me the stuff to go out on the street to play with for a half hour or so. In the case of film cameras, they give me the thing and I shoot a roll of film for a half-day or so. If they don't know you, you could offer to give a card imprint while you go off on your test. Try that at Future Shop, and you'll find it's a great way to have the usually attentive salesman act like you just dissapeared.
These days, it's pretty much Canon and Sony for the good stuff, but just because it's got the right brand don't assume it's a camera meant for serious work; these guys have to make models to attract boneheads too.
If you are looking for a Sony, try price checking and check for how current the model is at a factory Sony Store. Don't expect good service, it's not much better than Big Box, but because Sony doesn't want to antagonize it's retail chain, you will find the highest prices there, which can help you assess value to find your bargains.
Once you have a good idea of what you need and don't need and are ready to buy, don't be afraid to ask for a competitive deal with a good, helpful store that offers a different (but high quality) brand. Here's where your painful shopping at Big Box Ltd comes in handy. "I was just at ... and saw I can get a Blowfish 2000 for $999 with this stuff. I know your Pufferfish 2100 has these other fancy gee-gaws, but I don't want those features. Can you match the price?" Do this with cash (or whatever) on your person and tell them your buying TODAY. Feel free to ask the salesman for a card while mentioning that your cousin Ralph wants one too. Good luck.