Although I've seen and experienced a few of these upgrades on my personal machines. I have found that the first series "non-unibody" MBP's although actually, quite a bit easier to do. Seem to have Some fit issues, and never seems to come together "clean' if you get me.
It's a super thing to get that old Dual-Core out of there, it makes a real difference in what you can do. For me, unless I'm moving it to a Socket T, there just doesn't seem to be enough reason to do this upgrade. No offense, just the math. The cost of the replacement board, time and effort, risking damage to all of those little connectors, and then there's the Mac OSX upgrade...
My favorite trick is to get a Unibody (Used or broken for $125) and mod it from there. many more options and the board and socket is better and more useful.
So, as for help with your issue, just be aware, if you haven't taken the system apart yet, the A110n series is a solder on CPU, not really an upgrade option. The next 2 series are ZIFF sockets, much better, then 3rd gen with 775.
By no means is this impossible by any streatch, just do the board swap, don't attempt to re-flow job, it's pretty tricky!
Hope this helps,
My 2 Cents!