I'm perhaps in riverripper's boat - near 4.0 from a small, private, liberal arts school in the midwest. Quite happy with how things came out for me last year.
Here's what I say: no one factor is a 100% deal breaker. We all know about people with bad GMATs who get into (insert fancy school name here). The more positive data points you offer, the better your app will be, no matter who you are. And in my estimation, I would put having a bachelor's from (insert fancy undergrad school name here) lower on the list of data points. I would even contend that schools see undergrad institution as a point of diversity - one of my old professors at Tiny College used to be pals with an adcom at a semi-major b-school, and apparently she told him that she wishes they would get more small, liberal-artsy or state college applicants. There just doesn't seem to be much of a pipeline.
And who really cares anyway, as your alma mater is not something you can do anything about.
Next steps:
Do well on your GMAT.
Be thoughtful.
Write brilliant essays.
Get into school.
(And see Lepium's post on the phases of b-school for all the stress and disorganization that comes in between!)