Forget about Points.com. They simply rob you with horrible exchange rate. It's almost impossible not to lose significant miles after the transfer/swap.

People value miles/points very differently in their individual ways. Web Converter will give you some ideas of possble transfer between miles ( http://www.webflyer.com/programs/mileage_converter/).

This is a topic lots of folks asking and doing. I would recommend you to do a search using combonations of terms (mile transfer/exchange/swap/convert...) under the forums of your interest such as MileBuzz!, AA, UA, HHonors, Amex SPG...etc. You shall find quite some threads to answer your questions. Practice makes "search" better, you know. I learned to try different search terms to get the best results from FT because all the possible answers to miles/points are really here already!

As for Points.com, same deal. Do your own search at different subforums, so you can judge the good and bad yourself. Don't just take my words for it.

Good luck!