Buying a brand is basically buying into their way of marketing.
HP computers are always more expensive, as Cookie said, but it's important to mention why they are so expensive.
1- Support.
HPs support has the #1 tech support for computer machines, it still sucks, it still takes a long time, it still is a pain in the ass, but it's much better than other brands. For example, here in Canada, to get an Acer laptop repaired, you actually have to fill up a ticket on www.fixmyacer.com so they call you back. Kind of sucks if your computer is broken. Yes, there is always a backup hotline that you can call, but you can't compare HP's tech support to it.
2- Publicity : last time I've seen an Acer commercial was.......................... never. HP's on the other hand, got JayZ, Fergie and so many stars doing their commercials on TV, someone's got to pay the bills, and the consumer's that person.
My point was simply to say that yes, some brands, as HP and Apple in many cases, are going to cost you more, and you ARE paying for the BRAND. But that brand includes different things, including support, commercials, warranty coverages, etc.
What you should do is really check these things out when buying a computer. For instance, if you take an extended warranty or a service plan from FutureShop or BestBuy for instance, it might not be that important to have that good of a tech support, as the shops have their own HP, Acer, Toshiba certified technicians that will fix the computers themselves.
Something to check out when buying a computer.