how much for a system to run bf3/skyrim well?

[unwashed potato!]

i'm thinking of building a new system from ocuk and would like an idea of the cost.

i'm mainly needing this for work so thought of getting something half decent when win8 is out, but then would like to spend a few extra quids to make it able to play bf3 at decent enough settings and skyrim also.

i need just the machine and internals and win8, no monitor speakers keyboard etc.

how much would i roughly be looking at to get something half decent?

 

[unwashed potato!]

thanks guys. will come back here then when win8 is out and see what's the deal at the time. bit unrelated but does the ocuk finance option allow you to pay no extras if paid off in a set time, e.g. if paid off in the first year or earlier then you'll only pay the exact amount you borrowed?