Apple laptops, as far as I am concern are able to ROCK any other windows based machines out there. I have a PB 12" G4, decent battery life, it never freezes and it is fairly rugged.
My bro is into Toshibas. Pretty much all the Toshibas that he has had, that means 2 of them in the past 6-7 years have been very stable.
I would stay away from HP, I have had bad experience with their gear, so did my friend with her HP laptop.
DELL is fairly affordable, but you will get what you paid for in terms of reliability.
Not to discount the person who said that his wife's company owns massive amount of Dells, but Dells are very good in outbidding other manufacturers when it comes to Corporate accounts, thus, I do believe, without looking into the purpose of the Dells in the company, that the company decided to carry them due to price and not necessarily reliability issues.
LENOVO or the formerly IBM thinkpad line also seem to be very reliable, rock steady, although more costly.
COMPAQs have gone the way of the dinosaurs since they were acquired by HP. It is a true shame. A student I know has had their mother board FRIED within 3 months of getting her laptop.