Quick question about installation of mobo

If any of you remember some thin cardboard-like washers that came with the board, I didn't use them. I got to reading the case/PSU forums about grounding issues and wondering if those had something to do with grounding. From what I've always thought, you need your board grounded to the case pretty good, and the mounting holes for the board have metal around them so I didn't know exactly where the washers went and didn't use them. Are they really that important?

If it's what I'm thinking about,
They are used around the screws
that hold the mobo into the case.

Sometimes it is not centered, washers help you
tighten the screws, so they are secure.

Without shorting out anything around the mounting holes.

The mobo gets grounded from the backside
of those screw mounts.

I just used the brass standoffs....

Alright, just making sure so I'll have some peace of mind about it. Thanks.