Um, it IS a dual core.
Hence "Core 2 Duo". Basically the replacement for the Pentium Ds. Only a lot faster. Also, a Core 2 Duo running at 1.8GHz is much faster than a P4 running at 3GHz Fastest notebook processor thats a reasonable price is running around a 2.4 DC
However, its not that cheap.
Always make sure you get 2gb of RAM
Also, get Vista. After the 3-4 hours it takes to get used to the new start menu, and removing your mouse, its much nicer to use than XP. I havent had VISTA crash on me yet, only applications that would normally result in a BSOD under XP. Win Win@