I think you should only post when you have first hand knowledge of the subject, as others here have already said.

I think if you only got 1-2 responses from a thread, and always told people to just search for the answer, you would not build the community you have here.

Sharing the information you have is what makes forums work. The more you share the more you get to know people and it is what builds the friendships.

Dax

If you post then the person has several options to try, then he may hit the solution right on the head. POST.

I also sa why not post, telling the threadstarter who/what you agree with?
That's what the "quote" is for  
plus, it's extra reassurance when more ppl havee the same answer!