How many megapixels would be best if i want a digital camera for printing regular size (4 x 6) photos?

3 to 4 MP is certainly enough to get you a film-like 4x6 print. With prices coming down you'll be tempted to get something with higher resolution but keep in mind that the higher resolution comes at the added expense of additional storage, larger file sizes, and longer upload/download times.

Also remember that the key factor in producing a pleasing image is the quality of the lens -- much more important than simple resolution.

You need at least 4 megapixels to print decent 4x6 photos. Try to buy a camera with as many megapixels as you can afford--prices are coming down.

3 megapixels should give you good quality for 4x6's. The advantage of having more megapixels is that you could crop your image a little bit and still get good quality. For example, if you started with 6 megapixels, you could choose to print just a quarter of the image area and still get decent 4x6's

iBob's point can't be overemphasized: lens quality is absolutely critical--just like speakers in a stereo or home-theater system. As a _very_ rough rule of thumb, look to traditional camera-makers who have moved into electronics (e.g., Canon, Olympus, Nikon) rather than electronics manufacturers who have moved into photography (e.g., Casio, Epson, HP). This is less true today than it once was, however.

Also keep in mind that the printer/paper/inks have an equally large effect on print quality, and the cost of consumables was still in the 25-cents-per-image (dollar-per-page) range the last I heard. I've used Ofoto (Kodak) instead, and aside from the turnaround time, it's been both cost-effective and higher quality than the output of any home printer I've seen. (Which is to say, it's equivalent to regular Kodak prints--in fact, it _is_ Kodak photo paper, or something virtually indistinguishable from it.)

Btw, dpreview.com is an excellent site for reviews of digital cameras (parse as "D[igital] P[hotography] Review," not "d preview"), although it tends to emphasize the high end somewhat. It has full specs for most or all digital cameras from the last 5-8 years, I believe, and extremely useful customer reviews (in my experience, at least).