Do a search of this forum, Yep there are a few doing live capture via a laptop... I am using the MacBookpro for 1080i60 DVcproHD,, no problems..
HVX200>firewire 32'>MacBookPro 2.4/4 gig ram> sata express card (Addionics) > 2 x 2.5 sata 160gig mirrored Hard drives... Works just great Final Cut Pro 5.1.4.. Leopard 10.5.1..
I am not recording to the internal drive. The Express card is a different entry point than the firewire on the mother board. (the 400 and 800 share the same buss)
I am averaging a gig a minute with 1080-60i.. SO the mirrored 160gig 2.5" sata drives give me about 2.5 hours of HD video with a mirrored back up. Add the 400 dollar 24" LCD I just ordered and I should have a HD location shoot and edit rig under 9K..