I don't think so for reasons others have given. I had hopes for the i-pad - see my current posting in 'Our website' section. My i-pad was a gift, but in UK you could buy a reasonable laptop for considerably less money, without the portablity of the i-pad but with USB ports, and much bigger storage. You could always look at netbooks or the other makes of tablets, but there may not be mucch saving in price, and I understand some of the operating systems are fairly basic and restrictive.
I have a Toshiba 17" laptop which doubles as our DVD player. The sound quality is not all that good, but if you have a radio in the van which has AUX input you can probably cornnect the laptop to it and thus improve sound quality and volume. The increase in area over the more comon 15" models is very noticable. I understand the newer HP laptops have much improved sound quality.