Yes. Direct2Drive will give you one key to redeem the game on Steam. Once you've locked your copy of the game into Steam, you can download it (via Steam) on as many machines as you like, although you can only play it on one machine at any one time.
The other good news is that save games use "Steam Cloud", which means that you can access your saves from any machine - in other words, save any game on your home PC, and continue it hassle-free on your laptop later.