do you have anything that uses bluetooth, and are you likely to get anything that uses bluetooth? the only things that come to mind are wireless mice, cell phones and pda's (but a lot of pda's use wifi as well)...if you're unlikely to use either of those with your notebook, then I would go with the bigger hard drive (I know some people love the BT wireless mice, but are they better than the rf mice, and are there any issues with lag?).
...if you want to keep a lot of music files or have several different games on your notebook, than I would say go with the bigger hard drive. Think about HL2 and UT2004, and then think about all of the add-ons that the gaming community has developed for them (RO, Clone Bandits, etc. for UT2004, new ones coming out for HL2). Plus, you can add BT with just a usb thumb drive...