I have a large number of DWG files that I need to convert to PLT.  Does anyone have any suggestions as to how and what software to use to batch convert them?

This is "batch plotting". Depending on your AutoCAD version you can use either the Batch Plot utility or just the [CMD]PUBLISH[/CMD] command.

I am a real novice at this.  I am using 2006 version of autocad LT.  I tried the publish way and it converted the file to a DWF not a PLT.  What is the Batch Plot Utility?

There is a DWF/Plotter switch in the Publish dialog (on the bottom). Choosing Plotter allows you to save to PLT file(s) when your plotter is set to output to file.
 
Please note that PLT is not a format, just a file extension - you have to choose a specific plotter model.