I recently purchased an ASUS G73J and have nothing but praise for it so far and it may fit the mould for your future proof-ness.
Core i7 2.8 Turbo
ATi HD 5870 1GB DDR5
8GB DDR3
1TB 2x 500GB 7200rpm
17.3" Full HD 1920x1080
This retails for ~$2400 AUD, so it should be within budget dealing in pounds.
Although a different strategy may be to buy something low to mid-range budget with anticipation of replacing it sooner (2 years), than forking out more cash and expecting it to last the distance.
Also worth taking into consideration is the manufacturer's warranty service, I find that HP and IBM branded laptops have a global next-day repair service, whereas most others require you to do the RRoD procedure and buy a coffin etc. and wait 2 weeks, which may be downtime you can't afford.







