Whenever you spend £3000 you will get the most uptodate hardware; within 6 months it will be surpassed by something more powerful.
My advice would be to spend a percentage of the money on a good quality machine now, while retaining some funds for upgrading as newer components become available.
It will be easy to upgrade your graphics card, RAM, processor etc as necessary if you purchase a good quality motherboard now.
Sound cards / speaker systems for gamers are pretty good now and it is unlikely they will see any dramatic improvments within the next year or so.
Finally, purchase a good monitor - the best you can afford as that will be your main user interface for many years to come.
Good luck, Dio.
PS if you want to spend some of that 3 grand on consultancy, you know where I am! :-}