I personally would stick to the big 2, Nikon or Canon. Solely for the fact that there's a lot more in the second hand market for camera and lens, including the 3rd parties, you've got a lot of offering and flexibility to your budget.
I've seen pictures taken with the Sony and kit lens, I can't fault it in terms of IQ for something at that price tbh. User-ability wise, I haven't a clue but I'm sure like all DSLR, once you've played around you'll get use to the way it works. Be it Nikon, Canon or Sony.
I personally jumped into a Canon 20D because it feels like a proper camera, it's got the high FPS I needed for sports photography back when I first started and it was a bargain.
But to get you started, going for the Sony till you're sure which focal range you use most and perhaps when your budget stretches, you can sell off the A200 and jump ship. Don't make the best economical sense as I'm typing... lol.