spec me a good computer please ?

[colinicky]

Ok the last computer I built was when a 1gb duron was top of the range !
So I am looking to change it .Want to use the new one for some serious gaming & also for video editing from my other hobby of scuba diving .So help please was thinking of sli maybe am2 5200+ ,asus crosshair ,graphics I am totally lost as my current is an mx100/200 .So might need some hand holding on this one please be gentle

 

[colinicky]

budget?

I know this is going to drop me in it but not got a clue ,rather want a good computer than cut corners .If it ends up extreme so be it