On the other hand, if you want the greatest flexibility and an ability to do things like control depth of field, get the fastest shutter speeds, etc., then a DSLR is a must-have.
To be brutally, painfully honest ... Mac-Forums.com is not the best place to find the best camera. I would start out at
photography-on-the.net which is a mostly Canon-oriented site but also has some Nikon users. Which is ok, because cool people choose Canon.
Even for relatively slow motorsports like ATV, you'll want to compare things like autofocus speed and accuracy, burst rate (how many pictures can the camera take in a second), buffer size (how many total pictures can the camera take at that top speed before it needs to stop and do some computer processing to catch up), etc. You'll also need to determine if the weight (and cost) of a metal body is worth it compared to a cheaper, lighter, but less durable plastic body.
For a run-down on different Canon cameras and lenses, there is probably nothing better than
www.the-digital-picture.com in their "Photography Equipment Reviews" section.
A great generic starter lens for a Canon DSLR is the 28-135 f3.5-5.6 IS USM (you can learn what all that means at either of the sites I mentioned above). You'll pay around $400 for it and it will do literally almost everything you need until you have the money and skill to start picking more specific-purpose lenses. I've taken two different photos using that lens (and an old Canon 10D) which have been used in glossy magazine advertisements.
If you will have to take most of your photos from a fair distance away (100' or more), you could either go with the less expensive (and less rugged) 55-200mm f/4.5-5.6 USM II (which lacks image stabilization) or the more expensive (around $600)but infinitely better 70-200mm f/4.0
L USM ... which also lacks image stabilization, though.
However, the 55-200 and definitely the 70-200 will make it difficult to do things like typical up-close portraiture, or group shots because the focal length is long (in layman's terms, they have a "lot of zoom").
There is also a 28-200mm f/3.5-5.6 USM lens that runs less than $400 which is supposed to be ok, but I've never handled one.
Be careful stepping off this cliff, though. Digital photography can be an expensive habit. I don't think they make an Apple computer that costs as much as my photography equipment.
Good luck and feel free to PM me if you have any specific questions, especially about Canon stuff. If you decide to go Nikon -- which is fine, there is only so much room in heaven anyway
-- I know at least a few people on these boards are skilled Nikon shooters.