May as well buy it now, they keep dropping in price for the equivalent spec computer so waiter for a better one to be available for a lower price is a never ending wait.
Check the dell website... you'd be surprised, I've bought a few of the ones on the link below and have been pleasantly surprised by them for the money.
http://www1.euro.dell.com/content/products/pro ductdetails.aspx?c=uk&cs=ukbsdt1&id=vostronb_1 710&l=en&s=bsd
Oh the extended warranty normally only covers hardware faults... not faults caused by user error.