In the Order of Worship/Service, what is essential?

I thought I'd throw this thought out into the light of day. In our various church backgrounds, what do you consider as essential in your Order of Worship and what parts are secondary (indifferent) or to say, may help and not harm a Worship Service?
What is the main reason you attend church?
Grace!
tonygermain@msn.com
Micah 6:8

the main reasno
the main reason I attend church is so that my friends and family won't be crushed by my total absense. Its hard to go to a place that has no respect for individual opinion and can't change to meet the challenge of today because they are so afraid of their own ignorance they can't admit they were wrong.
Plus, as that one guy said in that one move--I got nowhere else to go.