Yes, I have noticed a significant performance improvement in my 12" PB 867 after putting the 512MB chip in. Since the new 1GHz 12" costs the same as the 867 MHz did a weeks ago, it is probable that the soon to be available 1GHz refurbs won't cost much more than $1200. I would wait to see if you can get the "new" 12" PB for comparable prices in a month or so. I bought my 12"er about 6 weeks ago, and I kinda wish I had waited although I am very satisfied with my PB.