Choosing a DSLR is more about the system than the camera. Good lenses last almost forever but bodies come and go. Nikon and Canon have the most extensive array of lenses and accessories and you can't really go wrong with either. I went through the process of choosing a DSLR a few years ago and spent 6 agonizing months trying to decide, finally choosing a Nikon D70. Last year, I bought my grandaughter a Nikon D50 and just now, bought my youngest daughter a Nikon D40 for her 15th birthday.
The only difference between the Nikon D40 and the slightly newer D40x is more megapixels. 6mpx is plenty for most people and doesn't usually require a computer upgrade to handle the larger files.
The older D50 is an outstanding camera but can only be found used or refurbished as they're out of production.
The key to taking good tank shots is the lens. A dedicated macro lens or a lens with near macro capabilities is best. One word of caution on the D40 or D40x is that they require lenses with internal focusing motors. Nikon calls that AFS. Plenty of good AFS lenses are available, though. Older lenses work but must be manually focused. The standard kit lens for the Nikons is the 18-55. It's inexpensive but is an excellent lens and takes great closeups. I went up a notch with my daughter's D40 and got her the 18-135 to give her more versatility with the zoom range.
I buy most of my stuff from either B&H, (probably the best online vendor of them all, or BuyDig or it's parent company, BeachCamera. They usually have the best prices on cameras and lenses but are higher on accessories.
If you want to go higher-end, the Nikon D200 is a superb picture-taking machine. Whatevva (Butch) has that camera with 17-55 lens, a superb combo. The D200 will probably be my next camera though Nikon has just announced a new D300 which looks to be awesome, though won't be available for a couple months. I'm in no hurry as my D70 is still working just fine.
Since you're close to Knoxville, you might take a trip down to Thompson's Photo and check them all out in your hand. They are very knowledgeable and helpful and I've bought lenses and stuff from them.
Here's a great database of all cameras with excellent reviews of most of them:
http://www.dpreview.com/reviews/specs.asp
Good luck with your camera shopping!
Dick
