Hey there,
I have the MPC/Ertl Return of the Jedi kit. I also couldn't find the Fine Molds kit, so down the road I plan to upgrade the MPC kit I already have. I believe it's the same mold as the new hope version you bought.
I did buy Falcon Kit's sidewalls over the winter. The resin casts are very clean (not a lot of air bubbles, if any). However if you're going for accuracy... you might want to scratch your own sidewalls. Don't get me wrong they're nice, but there are some small details that just aren't the same as the actual model. At the end of the day I'll probably take all my Star Wars reference books and build my own sidewalls.
Here is a good link and worth reading before you start:
Starship Modeler - ERTL Millenium Falcon
John Martin did an awesome job. I'll be following his advice/measurements for my build.
Keep us posted on your progress.