What is the difference between the Pentium 4 with hyper threading tech and the Pentium M with Centrion mobile tech? I am looking to buy a laptop in the $900- $1000 range. the 2 I am trying to decide between one (Gateway) runs a Pentium 4 and the other (Sony) runs a Pentium M. Is there an advantage or drawback to either processor, or is one a better brand. Prices are close enough to not be an issue. Thanks Everyone.