A lot of people say that renting is like throwing money down the drain, conveniently ignoring the fact that an interest only mortgage is effectively renting from the bank. The argument for buying becomes less convincing with a falling market. An example is given below. 

House in Weybridge

Sale: Originally on at £619,950,

http://www.propertysnake.co.uk/site/detail/9182876

it is now listed at £595,000

http://www.johndwood.co.uk/www/site/_page.php?page=propertyDetails&type=b&id=WEY070272&theme=buying_country

Assuming a typical IO mortgage of 6%, this would mean you were paying £36000/year, or £3000/month.

Renting:

Listed for rent at £360/week which works out at £1560/month

http://www.johndwood.co.uk/www/site/_page.php?page=propertyDetails&type=r&id=jlwe_3186&theme=renting_country

Throw in the fact that house prices now appear to be falling (by around 1% month on average - Rightmove have the latest numbers - see link below), and this place will cost you at least £7k more a month to buy rather than rent. Maintenance costs would also be a lot less on a rented property

http://www.rightmove.co.uk/pdf/p/hpi/HousePriceIndex17thDecember2007.pdf