MP are just a number. The quality of the processor and the image sensor are the most important factors.
I saw an interesting review last month while I researched the same topic (no I do not remember the site sorry) that compared the Nikon D40, a Canon 8 MP DSLR(whichever model is closest to the D40/D80 mid price point), and the Nikon D80.
Although the D80 outperformed the D40 in benchmark tests using test patterns and industry standards, the difference in real terms was negligible. They did the benchmark tests for picture sharpness, ISO capability, picture/color accuracy, and some other factors. Then they also took real world pictures (the same picture with each camera with a range of settings that they showed.) Both of the Nikons EASILY outclassed the Canon in picture detail and flexibility in real terms even though the benchmark tests showed not much of a difference.
Think about it this way....car manufacturers advertise HP ratings. We all know that there are many different ways to get to the number they give right? We also know that just because a car has 300 horsepower it is not necessarily faster than a car with 250Hp. The same holds true here. Hp is part of the equation that gives a car its driving characteristic...just like MP is part of a picture quality from a camera.
Consumers like bigger numbers, just look at TV's and the rediculous "dynamic contrast ratios" the companies advertise. Dynamic isnt even the actual contrast that you see when you watch the set (yes I work for a major electronics retailer and have been into HT systems for many years now.) As log as the number is bigger then consumers like it.
Heck there are point and shoots with 10MP. You really think that their picture is better than the Nikon D40? I can safely tell you they are not.
I chose the D40 based on the fact that I am new to DSLRs, and the real life difference of the D40/D60 are so minimal that I could not justify the extra investmet. Maybe in the future, but for now I can tell you the D40's pictures are amazing.
In fairness I have heard good things about the Sony Alphas also (ever since Sony bought out Minolta anyway!
) I do not think you can go wrong with either piece honestly...guess I am just a Nikon whore since I have one! lol. good luck.
p.s.Do you have a Mac or a PC?