I second Canon. I'm a graphic designer & I maintain a full array of pro photo gear and all of it is Canon. The other option is Nikon, and the reason I'd recommend these two companies is that their primary product is photographic equipment. ALL of their R&D goes into cameras, and more importantly LENS technology & you'll be benefiting even with the consumer level camera.
Also, I'd recommend COMPLETELY disregarding the whole notion of getting the camera with the most megapixels. You can get a kick-ass 4mp camera which will more than suit your needs for general photography. Larger megapixel cams are only necessary if you're going to be printing poster size images. If you're just going to be doing 5x7's or even 8x10's then a 4mp cam is an excellent (and much cheaper) way to go.
Try B&H Photo (bhphoto.com). They're very reputable & you may find a gem in their used camera dept.