If your laptop's Core 2 chip is 64 bit capable (some Core 2 chips are not), I would go for 64 bit, simply for the sake of saving yourself headaches later. If you decide to upgrade to or beyond 4GB of ram later on, but install a 32 bit copy of Windows now, you will have to back up your data, wipe out the hard drive and do a clean install.
There probably won't be a performance gain with only 2GB of ram installed, but it's better to go the x64 route now if you can, than to stick with 32 bit and regret it later.