Most non-commercial table saws are 10". Even on big Powermatics and similar saws cutting a full sheet of plywood by yourself is next to impossible without additional fixturing (infeed and outfeed tables, etc...)

You don't mention the saw you have (portable, floor standing, etc...) but Delta is a good name. You need to go to Fine Woodworking and find either some articles or books on how to handle large panels and using a table saw.

The saw you describe at the installer's is a panel saw. Unless it's something the likes of which I've never seen it's a lot more than $500 and not especially accurate.

• http://www.taunton.com/finewoodworking/index.asp