I take ALL my pictures at 2160x1440 (3 Megapixels). Sometimes I even take shots in TIFF mode - 9 MB each... :Q (My 3 MP JPEGs are in the 600-700 KB range usually, and the compression is just a tad too high for my tastes.) For good prints, the photo shops recommend at least 200 pixels per inch. For my 3 MP images, I only get 180 ppi for an 8x12 print, although I think it's pretty damn good. The 133 ppi from a 2 MP camera is pushing it though, and anything less than 100 would be unacceptable IMHO, unless it's for posters. Plus, having extra pixels allows you to crop.
If you're planning on replacing a film camera, I would suggest a 2 MP camera at the bare minimum, and preferably 3 MP. However, not all 2 MP cameras are the same. Same goes for 3 MP. If this purely for web viewing, etc. then lower resolutions are acceptable though.