Which? Advice: Computing: http://www.which.co.uk/advice/computing/
A very useful source of advice for everything to do with computers (mainly PC's but there's some Macintosh too), including "how to" sections and buying guides.
"Setting up and maintaining" includes buying guides, but also covers topics such as installing extra memory, encrypting data, using the control panel, and creating Vista accounts. The buying guides explain the important features to consider and include links to producct reviews although a subscription is needed to view these.
"Using your computer" offers advice on email, iTunes, blogs, Excel, Word, OpenOffice, PhotoShop, PhotoShop Elements, Gimp and much more.
"What you can do online" covers everything from Twitter to eBay.
"Managing & protecting your information" includes antt-virus, spyware removal, parental control and safety online.
"Using your mobile phone" is not just for those sad people who have to have the latest toy.