meh, IMHO its not worth spending an extra $100 for another 20-40 gigs of storage on a laptop drive. If you absolutly need the space, an external drive is more worth your money. Buy a 200 gig drive for around $100, and a $30 enclosure for it, and bam, for what it woulda cost you for another 20 gigs internal, you just got 200 external.
AND its portable, easier and faster to transfer to your desktop or to a friends computer if they have usb2 or firewire....its just a more well rounded solution in my opinion.....not to mention when the seagate first comes out its going to be @$$ expensive!