Anyone that's seen my van knows that I'm a proponent of more information is better.  I think it's a little more important for me to list services because my company name (Santa Barbara Smarthomes) is a little more ambiguous.

If you have "Audio & Video" or "Home Theater" in your name most people will already get what you do, but what if you also do lighting control, cameras, central vac, networking, etc. 

I've had long time customers follow me outside and casually look at the van and say "I didn't know you did -insert service here-" after seeing the van.

One of my competitors here in town has a fleet of Sprinters that simply have their company name, number and their slogan "purveyors of effortless access to everything amazing".  It's very classy and they have good name recognition in town, but for someone who doesn't know who they are I'm sure it leaves people guessing.

Innovative AV - Here's a couple pictures of my van that might give you some ideas.  It looks lke you're going for a similar layout to what I have: