Hi Linda,
It looks like, indeed, the body is not as important as the lenses are.
But as I was looking myself for some information about my coming purchase of a DSLR, I have come across an interesting article concerning sensors (sensor quality and size, as I have understood it, seem to be one of the most important things to check in a digital camera - as far as the camera body is concerned - for good picture quality).
It seems that there is a great deal of quality difference between CCD sensors and CMOS sensors.
Here's the link to the article :
http://www.spyshop2000.com/cmos_vs_ccd.htm
For your information, Nikon D40, D40x, D70, D80 and D200 all are equipped with CCD sensors.
I have read that some Canon cameras like the 20D - I don't know for their other products - are equipped with CMOS sensors.
Hope this helps,
Karine