Sometimes you can go into a store, say what you want your computer for, and they'll fix you up with one.
ANSWER:
I would be very, very careful about this. It's not a good idea to go out computer shopping and depend solely on a retailer for advice unless it's someone you trust, and never do it at a big box retailer. They may or may not know what they are talking about, and a lot of employees will gladly take advantage of a customer in order to make a sale, especially if there's commission involved.
This is very true in the UK. The big chains are useless, they will deliberately lie - to get a sale. Proved on TV watchdog programs. They do not employ people with computer skills, just anybody who wants a job. Try to return the product and get a refund because of misleading sales tactics, may result in a long and costly legal battle. They know this and can afford it, they also know the average person can not.
So, go to the small independant shops, they rely on goodwill and repeat business. It is probably the same in other countries.
Sorry, what? The TV told you that all large PC retailers are stupid/evil and you are actually claiming that as evidence? Did you WANT someone to come and point out your stupid?
Furthermore, your picture is inaccurate. The problem with places such as PC World (which will henceforth be the main retailer discussed) is that they are inconsistent - they do tend to hire people who are very good with computers, but simultaneously staff who don't know what a monitor is. This also is subject to local variaton - so I know that my local one at home requires people to demonstrate computer skills as part of the interview, but the one in Oxford will hire anyone (or so they tell me.) If you work with their core departments however (bypassing the poor confused part-time staff), they are quick, not overly expensive, and good at what you want them to do. I have heard them endorsed from senior types in IT companies as well, so this is not just my isolated opinion. The trick is to not go in entirely uninformed - so that you can recognise whether you are being served by someone who knows what they are doing.