Digital zoom does not capture any additional detail than the maximum optical zoom of your camera. Instead it uses interpolation (the process of determining the value of a function between two points at which it has prescribed values.) to make a part of the image larger by adding pixels.  Unfortunately, this means that the camera guesses how and where the new pixels should be added.  This is only giving the illusion of increased detail and can sometimes make the picture less clear or even incorrect.

Also, using the digital zoom will make it more difficult to focus.  I higher megapixel camera will give you more freedom to edit using a program, but if you want to take a lot of close-ups, I would suggest investing in a higher optical zoom or telephoto lens.