If the concern is only for web posts, a 3 inch by 5 inch "on the screen" at 72 dpi screen resolution will contain (3 inches x 72 dots/inch) x (5 inches x 72 dots/inch) or 77,760 pixels. Obviously, ANY camera you are likely to find for sale at retail will take "adequate" pictures for web posting - IF you can take exactly the picture you want to post.

Any processing you may want to do before you get the "postable" picture is going to throw away quite a few of the pixels, so it's well to start with "as many as you can get."

A couple of years ago, 2 MP was about the best available in "consumer cameras." If you find a very good deal on one with 2 Megapixels and if web stuff is all you need, then that may be adequate.

More recently there were lots of 3 MP cameras at consumer prices, and some of them may be pretty cheap now. For "good" prints you probably should have a finished picture at 150 dpi or better. If 5x7 inch prints are the most you'll need. (5 inches x 150 dpi) x (7 inches x 150 dpi) = 787,500 pixels. You can get that fairly easily even from a 2 MP camera under ideal setup conditions, but "typical normal amateur" preparation steps such as cropping etc will often throw away half or more of the original camera pixels. If possible, a 3+ MP camera will give you a lot more versatility.

With careful composition before you take the picture a 3 MP camera can easily produce very decent 8x10 inch prints, but cropping and color adjustements, etc., will eat up the pixels that come from the camera. Current recommendations put the minimum acceptable camera at about 3 MP for casual print users who may want an occasional enlargement. If you're willing to be really careful about setting up the shots, and take only what you will want in the final print to minimize cropping, you can sometimes get reasonable 8x10 prints from a 2 MP camera, but it's a lot more work.

If you get started with "working over" the pictures you take, you'll find that you'll probably want to do quite a bit of cropping and enlarging of little pieces of original images, and for this reason getting as high a pixel rating as is affordable is strongly recommended. It doesn't make any difference how many pixels are in the picture - it's how many pixels are in the part of the picture you want to crop out and enlarge.

For some people, 5 MP cameras now are pretty "affordable." I'd get that if I could, but I'm not one of those people at the moment. For anything above about 3 MP though, I'd want a lot of other features; so if you have only a 3 MP budget now, look for one with fairly simple "snapshot" features.

Recycle time (to save one shot and be ready for the next one) is a RPIA (royal pain in the ass) with all early model digital cameras, and only a few of the the newer ones have really cut into it. It would be a key feature I'd check out if it comes down to choosing between a couple of consumer grade cameras, but it may be difficult to get useful info. Shutter delay is also annoying, and some do a little better than others. Check it out if possible.

Anything 2 MP or better can make decent web images but 3 MP makes it a lot easier and should be reasonably affordable now. Get as much as you can afford, and you'll use the camera longer before you "really need" a better one.

John