From what you describe, it sounds like annual review results were unexpected for you.
If this is the case, consider contacting HR guys in the company and raising this issue to them. No need to dispute evaluation of your strong and weak points, focus strictly on the fact that review outcome has been unexpected for you, the employee. There is a good chance that this will be taken into account.
Firing at will may be 200% legal, but this does not necessarily mean that performance review system is purposely designed to enable that. In fact, opposite is more likely - that there is sort of protective measures provided do avoid performance reviews working that way.
- My friend once mentioned that when he was a manager at Intel, he even saw few annual reviews "reverted" when there was an evidence that outcome has been unexpected for an employee. Not all companies may be as strict at enforcing a policy like that, but in my experience, similar guidelines were more or less officially supported everywhere where review results involved subjective judgement of the managers.
Thing is, when company is unable to establish objective and transparent performance review criteria (as an example, criteria at Fog Creek look pretty straightforward) - when the system is not sufficiently objective, company has to involve subjective judgement of the managers. But this in turn exposes a company to the risk of senseless decisions that may be taken by some of the managers.
Requiring review outcome to be expected for employee (even negative one, like I knew, I knew it's coming!) can be used to offset the risk of manager pulling arbitrary reasons out of thin air and evaluating employees irrelevant to their performance. There are other approaches attempting to address this issue, like 360-feedback etc, but diving into this would rather be a subject of a separate question.

Now, I would like to say a few words about details of your review.
grades on my projects... were poor because there were discussion in the project (which I discern as meetings). The report said, the quality of work was otherwise great...
I've been once graded like that. Did not end with firing in my case, but nevertheless turned out painful. Quite painful. Also, I learned a few things that later allowed me to setup a more comfortable er divorce with a company.
First thing is, whenever there is a performance review system, check their rules and criteria.
- Management and HR may tell you it's OK, it's totally objective and transparent etc etc - but don't forget it may be just their job to tell you so. Don't blindly rely on that, don't expect it to be that way unless you check and verify that yourself. After all, "transparent objective" criteria imply that these are easy to discover, understand and evaluate - if you find out it's not so, well, you better assume that it's either not transparent or not objective or both.
If you find out that review criteria do not completely and clearly connect to your technical achievements, well, you better assume that subjective judgement of your manager plays a substantial role in the evaluation.
If this is the case - and from what you describe it looks like this is the case - this means one can not plan annual review to go like this:
4 successful projects => great work
Instead, one has to expect something more like this:
Positive: 4 successful projects
Negative: 3 times hurt someone's feelings
---------
Balance: ...
...well, outcome for above is really hard to predict, since "balance" mixes objective and subjective points.
How to generally "accommodate" to review system that involves subjective evaluation of the manager could be a topic for another, separate question, but one thing is for sure: ignoring its specifics would be quite risky.