the bigger the res, the better the quality (hence why all the fuss about HDTV and HDDVD/BluRay etc)

Also means the bigger the res, the bigger the pictures can be printed before looking "strange". We had a photographer come in a little while ago, supplied us with low-res (good for emailing 600x400) and high-res (2000x3000) on a CD. We've printed 4 off at about 8x12" and one to come even bigger (for our bedroom wall) - they look FANTASTIC