Being a sophomore and right in the middle of all this, I think I'll comment
I recently took the PSAT's last october, and in this case it does not count. I actually scored higher than 99% of all college bound juniors, and it means nothing because I am only a sophomore. In this sense, the PSAT can be a preliminary test. when you get to your junior year, however, the PSAT can win you a 5,000 dollar scholarship, not to mention it goes on your college transcript AND you get a letter sent to 3 colleges of your choice reccomending you. THAT is major.
The SAT's, meanwhile, are taken in April or May of your Junior year. This is currently graded on the 1600 point scale, but it is soon to move to the 2400 point scale, essay and all (I am the first class to take this, yay 06ers).
I can tell you now, almost every school I know in New Jersey, New York and Pennsylvania are Psat/Sat oriented. There's my 2 cents.
BTW: Despite the fact that the sophomore year PSAT's do not go on your college transcripts, nor are you elligible for National Merits, I have been receiving numerous letters from colleges regarding my grades (about 15 in the past 2 days). No parent should let their child take the PSAT's lightly, as they are an important step in getting colleges to recognize you (or at least begin to).
NJ Pitch