Try onOne's Genuine Fractals for enlarging fotos. Alien Skin has their Blow Up which does the same thing. I use Genuine Fractals; works great! Of course, the old adage still applies, "garbage in, garbage out". Both companies offer trials so you can see if their software will address your needs.

-Andy

http://www.ononesoftware.com/products.php

http://www.alienskin.com/