I just had a bad experience with that ram in my 15" PB. I got it as a gift on Friday, and put it in my powerbook. I was a little nervous becasue I was running video from my powerbook for a show I was involved in this past weekend. On Friday night it worked fine, but on Saturday, my PB would freeze up like crazy. On Saturday night, I took it out and everything worked fine for our Sunday show.
I did use the Apple Hardware test and it said that everything was fine. I am going to return it and get a different brand.