Hey Banquo,
Here are some of the good sites I have bookmarked that I go to for reference and reviews:
http://www.dpreview.com/ (probably the best)
http://www.kenrockwell.com/ (second best, heavily Nikon biased though)
http://www.imaging-resource.com/
http://www.popphoto.com/
http://www.dcresource.com/
http://www.smartratings.com/photography/digital_cameras
I probably sound like a Nikon salesman, but I am very convinced the Nikon D40 is the BEST bang for the buck. Period. You can get the camera body and the 18-55mm kit lens now for $449. That is an outstanding deal on a very user friendly camera and a SHARP lens. The D40x is a couple hundred more, but besides it having 10 megapixels vs. 6 from the D40 - the other differences are minor. (shooting .5 frames per second more, having ISO 100, etc) Those seem small to me and didnt seem worth the money. It's been noted that D40 has much less noise than the D40x too.
Also, if you get a D40/x you need to know about lenses, you cant slap any Nikon or other lens on there and expect it to work. Only Nikon lenses labeled as "AF-S" will auto focus on these. Sigma's equivalent is "HSM". Both of those will also meter too fine.
You run into issues when you put any other glass on the body. I can mount pretty much ANY nikon lens, AF-S, AF, AF-D, AI, AI-S with no problem,
if I don't mind manual focusing and manual metering. For some people, this isn't a problem (I'm one of them). What that means is instead of pressing the shutter button half ways and the camera auto focuses, you have to manually adjust the lens into focus. Not a big deal really, there's even a handy "focus indicator" on the lower left of the view finder that comes on when focused.
Gotta run - Let me know if you need any help.