I traded my son's laptop in the other day and only got £50 off, gutted, but nonetheless it was a truly rubbish laptop with less than 500mb of ram on it but qualified for the deal and wasn't worth anything. So it might be worth you buying a cheapo unit to trade in as now you will get £70 off spending £299 or £100 if spending over £500. There is also Quidco available on collect in store too, and 0% finance if you need it.
*Limit of one trade in per new laptop purchased. Trade in unit must be a laptop and must have one of the following processors: Intel® Celeron™, Intel® Pentium™ 4, Intel® Pentium™ M, Intel® Pentium™ dual core, Intel® Core™ 2 Solo, Intel® Core™ 2 Duo, Intel® Core™ 2 Quad, Intel® Centrino™, Intel® Extreme Edition, Intel® Core™ i3, Intel® Core™ i5, Intel® Core™ i7, AMD Sempron™, AMD Athlon™ X2, AMD Turion™ X2. It must also have an optical drive (e.g. CD/DVD), power up and log into an OS, include the correct power supply and battery, not be locked by a password and not have any significant cosmetic damage, i.e. the keyboard and screen must be undamaged and the casing and hinges intact.** 0% APR Typical