Tesco are currently selling the Acer extensa 6602 with £100 off. You get 1.7 ghz intel centrino with 2mhz L2 cache 533 FSB, 512 RAM, 80Gig HD DVD +RW dual layer 15.4 in screen. cost £598 and with a 3 year warranty.
Acer is giving the warranty. The laptop can also be returned to Tesco within 28 days if you are not happy with it. The lady told me to have a good play around with it and if it's not suitable for my needs then it can be returned and refunded. Included is also an international travellers warranty with Acer which is valid for 1 year.