Thanks. This worked!
I went to this link to download the appropriate file.
http://www.2shared.com/file/wJ8RpDPt/tools_v34.html
That gave me the right tool.
Because the file was a 7z file, i had to download WinZip to unzip the file. then I added the Pluggin using the Add New Pluggin button at the bottom.
I also placed my serial number in the plugin using the Customize Plugin button at the bottom.
I closed Calibre and reopened it. I pulled my purchased book from the Kindle and i was able to convert it to MOBI and i placed it back as a MOBI to test to see if my Kindle would recognize it and it did.
Thanks!