there are many people using sony vaios and toshibas in the field, but there are many laptops which can handle the task. just about any laptop you can buy today will have more than adequate specs to be capable of recording...however, you will want to make sure you load the recording software on a separate partition with it's own OS (dual boot).
i won't go into that, but look at the 24 bit faq -
http://www.24bitfaq.orgback to the laptop, some things you'll want to factor into your decision...portability, size, battery life, capacity for external or 2nd batteries, durability of the machine, and disk space and memory. you'll want plenty of gigs for storage and processing.
then of course you'll need a soundcard, many many options here. decide if you want to patch, run mics, etc. and read through some of the forums here for more info on that.
HTH
josh