mate i wouldnt get the ones they sell in pc world or toys r us
check out the audio laptops from these sites:
http://www.dolphinmusic.co.uk/d2/page/shop/browse/category_id/cfc873c36f01d06f32a7ee28e97f1d15
http://www.nusystems.co.uk/buy.asp?b=11&price=Audio_Laptops
http://www.sub.co.uk/
also check out midi interfaces @
http://www.absolutemusicsolutions.co.uk/
http://www.turnkey.co.uk/tkweb/minorclassbymajor.jsp?majorclass=Computer_Hardware
with mobile firewire soundcards you can power them off the firewire port on your laptop. so you can go sit out in the garden and make music (basically not have to plug your soundcard into a mains socket). also really good if you do some DJing cuz you can record live sets really without having to plug into a wallsocket.
really good firewire mobile soundcards are:
edirol FA101. 10 in, 10 out. 2 preamps, S/PDIF in/out, funky looking red breakout box
m-audio firewire 410. only 2 in 6 out. 2 preamps, S/PDIF in/out, funky looking breakout box (but with cheapy plastic rotaries). cheaper than the edirol.
presonus firebox. 6 in, 8 out. 2 preamps (really fking good ones too), S/PDIF in/out. most expensive of the lot.
i wanna trade in my delta 1010 for a presonus firepod (10 in, 10 out, 8 preamps [!!!], digital in/out, rackmountable soundcard), but i wont get a good resale value on my 1010. shame cuz the firepod looks amazing.
a laptop with a fast CPU (the fastest you can afford + memory to support it) + an external firewire soundcard like a presonus firebox is a pretty sweet setup to make music on. good luck finding a decent machine.