Hi everyone thanks for the replies!!
I just thought I'd mention that the 640m is about $1090USD and the 710m is $1224USD.
So far...everyone has said the 640m. I know the 640m has much better features with the duo core processor, ram, hdd and all that. It's also cheaper than the 710m. The only thing that's keeping me from buying the 640m is the fact that the 710m weighs a lot less!!
The thing is, I don't want to buy the 640m then realise that it's too heavy to take around with me. The 710m is only 4.1lbs, are its specs that bad? I thought the 1.7Ghz processor was ok lol.
Battery life isn't a big thing for me because everywhere I go there is an AC outlet I can use.
Thanks for the laptop suggestions ArizzX and PerfectSK but Newegg doesn't ship to Australia and I can't find those laptop models here in Australia.
Weight is pretty much the main issue for me.
Thanks again for the replies and keep them coming!