Check my Sig - Just got it about a month ago! though the frame rate is between 15 - 25, seems flyable (been busy playing others games on my laptop)!..... only time/ patches will tell if the frame rate will improve!
EDIT: I did some research about upgrades too..... these days its possible, but finding the right laptop and parts is difficult! Not forgetting that you will void your warranty! Ebay is the only place ive found new/ spare parts for laptops!
For example!
http://www.ebay.co.uk/itm/NEW-1-5GB-...#ht_688wt_1139
http://www.ebay.co.uk/itm/New-Intel-...item3cba360ed1