The current exterior door in my house is in need of replacement. It is an old wooden door which does not seem to be particularly heavy and hence probably hollow. It is ugly, it is drafty, and to top it off it has a giant window in it which seriously defeats any concept of security. The door also includes a side light which makes total replacement cost prohibitive at $750+ for the door/frame/sidelight. I have no problems with the sidelight and frame so would prefer not to touch them if possible. What I would like to do is just replace the actual door. My issue is that it has irregular dimensions due to it's age (1960s). It is exactly 31 15/16 " wide by 79.5 " tall. After visiting numerous hardware stores it seems that modern, as in newer than the 70's, doors are actually 31.75 x 79. The guy at home depot told me not to worry about it, that it would be close enough and that I could just take care of the difference with some plastic weather stripping. Before I go and commit to this I wanted to get a better opinion. Given that the dimensions are only ballpark close (new door is .25" less wide and .5" less tall), could I really get a good enough seal to keep out the chills? Is this something that people actually do or do I HAVE to replace frame and all? Any other options?