I have a Dell XPS15, bought in 2008. It currently runs a Core2Duo 2.4Ghz processor and 2GB of DDR2, 667Mhz RAM. I want to upgrade the RAM and wanted to know if along with the RAM capacity I can also get a faster RAM, i.e., maybe a 800Mhz or 1066Mhz. Will my system support that? Or will I have to be content with a 667Mhz upgrade?