Does the number of megapixels on an slr matter?

I'm looking to buy a nikon camera, but am wondering if the number of mega pixels matter. Like the nikon d40 has only 6.1… The nikon d3100 has 12.4… Does it affect the pictures if you have less?

Added (1). Sorry i meant a DSLR.

For 99.9% of us, it doesn't matter. I've seen magazine quality photos taken with the D40.
Put two 5" x 7" 's side by side, and you can't tell the difference.

I have an old Fuji Finepix I bought when digital's first started coming out with 5mp. I have beautiful 11x14's from that camera. Just be sure to set the camera to maximum quality. In other words use the setting which yields the LEAST number of pictures available. So I don't consider megapixels as a buying criteria any more.

Comfort of handling and seeing thru the viewfinder are MOST important! And choose a major brand.

Canon, Nikon, Pentax.

p.s. I don't care for the way Sony does business in my personal experience.

Just to clarify an SLR has no pixels since it's a film camera. A DSLR is what you're asking about, that's a Digital SLR.

For the most part no, it doesn't matter. More MP only matters if you're planning on very large prints such as posters, billboards and the like. For average home use no.

Wondering if Nick P had same camera I bought my daughter, the S5200 which also produced very good 11X14 enlargements at 5 MP. To most of us it doesn't matter how many megapixels a dslr has. Nor should it really matter to anyone buying a point and shoot unless it has too many and starts deteriorating the quality of images.

For dSLRs it doesn't really matter.

Camera companies push pixel counts higher and higher because they painted that whole picture of more is better years and years ago, and now they are stuck. So they add pixels to sell new cameras.

But nobody really answered why it doesn't matter for dSLRs that much, or at least not as much as it does in compacts.

The image sensor in an entry level dSLR has between 8-12 times the surface area of an image sensor found in compacts. The tiny image sensors in compacts have very bad performance for two reasons, that tiny sensor and too many pixels making matters worse. Noise is the result, even in decent light.

Sadly though, it gets more complicated. That 6.1MP Nikon you are looking at is very old, probably 7 years old. You can't compare it to a new 2013 12MP or 16MP dSLR sensor. As image sensor makers make improvements, they can negate the downside of adding more pixels, well usually.

Don't worry too much, just get whatever dSLR you can afford, that has the features you want. An old 6.1MP dSLR will destroy a brand new compact camera with 16 megapixels, every time.