Help with Muffler Replacement

My 2006 Prerunner access cab 4 banger had dual exhaust and a K&N air filter when I bought it. I meant to replace the muffler with a quieter muffler but didn't get around to it. Recently, I noticed a vibration at a certain RPM, and assumed it was the muffler. An inspection revealed that the muffler has rusted and there is a hole. Would a rust muffler cause the vibration I was hearing?
I think I am going to replace the muffler and need advice:
If I go back to a stock/quieter muffler, will I loose much performance?
What type of muffler do you recommend?
should I order it and install myself? I am somewhat mechanical but don't have many tools and haven't done a muffler job before. How hard is a muffler replacement? Do you need to weld?
The Walker Quiet-Flow Muffler on Auto Zone seems cheap and adequate.
Any help would be appreciated!
DB

 

I'd crawl under the truck (when everything cooled off) then identify the part that is rattling. It could be a hole in muffler that rattles a heat sheild. Only way to know for sure is to look/tap around to find it.