If you're going to buy a PC from Dell keep reading the papers looking for decent deals. Normally if you see one in the paper in one of their ad's for e.g. £400 if you actually go on the net it ends up being around £700 even if you add the same spec!!! Just ring them and tell them exactly the price you see infront of you and make sure everything you want included is there and they will (normally) oblige. I did and got mine for about £400. It's 3Ghz, 80GB Hard disk, 48x DVD +/- RW, Flat screen PC with Windows XP, 40watt speakers with free 18 month subscription to Norton Anti-Virus, Tiscali Broadband and all the other fancy shit a while back, and even that's expensive to what you could/should be getting but would of been worse if I'd trusted the website!!
For DELL you need the e value code to get the best deals, if its in the press its probably printed on the bottom of the ad.
The price in paper usually does not include their warrantly plan. On the website it does, so you when customising you need to delete the warranty (you get one year anyway) to match the newpaper/offer price.