I must say I totally disagree with the last comment, sorry Roll Right, no offense
From what I know from many graduate students already attending a PhD in Computer Science in the top 30 universities, it is pretty much the absolute contrary:
For every university, the TRUE point is RESEARCH. It's what a PhD is about, right ?
- In CS, #1 universities like CMU consider research experience has an absolute requirement, and BTW the first ( the only ?) criteria of selection.
- University below the top 10 will start to check the GRE if you come from an unknown school, but only AFTER the statement of purpose, the recommendations letters and the transcript.
- Lower rank universities are not so appealing for "good graduate applicants" (meaning applicants with research experience), so they receive application from candidates from more unknown universities, with no research experience. So they use the GRE as their main criteria because of the need to base their decision on something common to every applicant.
stefunny is the perfect example of all of this.
This is not what I know from my "experience", I am just applying for the first time for next fall. But it is what Dr. Mor Harchol-Balter from CMU (in those times, it was in 2004) say in this advice-document : http://www.cs.cmu.edu/~harchol/gradschooltalk.pdf , so I consider this good advices coming from someone who is part of the admission process at CMU.
But of course, applicant good enough to have research experience in top-level schools usually don't have problems to get perfect GRE scores...
In my case, I have no research experience, I am an international and I come from an unknown university... I am applying in universities between the top 20 and top 50, so according to what I said, if it is not impossible, it sounds pretty bad from the very beginning, so I had to sharpen my GRE scores (along with a LOOONG time working on the statement and getting pretty good recommendation letters from my profs) in order to at least balance my application and make me look like an average applicant.
But I agree with Tufnell, what apply for Computer Science can be the opposite for History ...