NEED HELP WITH NEW ALIENWARE M17!!!!!!!!!!!!!!!?

you can use RAM that is faster then what your motherboard specifies, so in this case the 1333Hz could be a replacement for your current 1066Hz RAM, but don't expect to see a significant difference, the guy who said his ran great probably only ran great because of the RAM upgrade in memory and not in speed, a 2GB to 4GB upgrade is what makes your m17 perform better, so you can use it but getting a 1066Hz would have the same effect