Welcome to the Q&A Board Snapper,
Boy, that's a difficult question to answer because it depends on how much you crop.
With a two megapixel camera you should be able to get an excellent 4x6" print and a good 5x7" print. But if you crop too much then, yes, your prints will become pixelated. In my experience, no matter what dpi your printer is set on, it will not eliminate that problem (there are some photo printers which have settings to help reduce the fuzzy look but they aren't always effective).
A few suggestions:
- Make sure your camera is set to it's highest resolution and quality. Digital cameras have two separate settings to select image quality.
- Try to move in closer to your subject when taking a photo. This will reduce the need for you to crop
- When you must crop, keep it to a minimum
Related reading:
Megapixelshttp://www.digicamhelp.com/what-is-a-megapixel/Print qualityhttp://www.digicamhelp.com/working-with-digital-images/printing-resolution.htm