you wanna be lookin at a £1000 /$1800 pc
core2 duo 2.4ghz +
4gb ram
8800gt /gts /gtx depending on the price u wanna pay but any 8800 should be fine
win xp is fine
500 - 600w power supply
hard drive is up2 u, suggest somet like 320gb depending on your file sizes
dual-monitors easy with new graphics card coz windows just detects em both just plug ur monitors into the card
simple as