I've read in multiple places that you're essentially a fool for not upgrading the memory chip when you purchase. But does it make sense to pay $100 now for 512 and an empty slot than buy an extra 512 for $140 and have 768 total (but no empty slot)? I don't see why I'd need more than 768 within the life of this machine. On a side note, why is the superdrive so much incentive for people to buy? Do that many people burn DVDs?