honestly there is a slew of new processors at the horizon. the penryn based ones for example. but having bought a dual core lappy very recently i can say 1 thing -- the AMD lappy that i have is 1.9 gigs dual core. the intel 1.6 dual core is far more expensive than the AMD ones... and I haven't heard of something more than 1.6 gigs.
b/w dual core and core 2 duo, i tried out a celeron 1.86 as well while deciding my purchase. if u r planning to run either xp or any linux distros, u don't really need a core 2 duo. a celeron proccy with at least 1 GB RAM is more than enough. my dual core which has xp doesn't feel all that faster than the celeron (really). I believe that this is because multi-core processing is only required for a limited number of applications. for all others, a single core is good enough.
i hope that someone knowledgeable about multi-thread applications would be better able to explain how multi-cores come into use.
but c2d is better than dual core. i don't think battery life would be so much of an issue, or for that matter heating. my dual core lappy rarely gets warm. could be because the applications i run -- open office, itunes, firefox, VLC -- do not need so much processing power.
rest, it's up to you. good luck
