I bought my 600m back in April when it costed about $100 to get 1.4 GHz as opposed to a 1.3 GHz chip. I also recently saw a number of 1.4 GHz and up Pentium-Ms on pricewatch.com. The upgrade's not urgent but can someone recommend how to go about determining when the benefits of upgrading outweigh the costs(or are about the same)? Thanks.