Upgrade help ! £700 system needed

[Scoobs]

@ the mo i run a p4 3ghz(about 18 months old) ,asus p43800 1gb 3200 ram and a 9700 pro.

Its a while since i built this and want to do a new one.

Do i go P4 or AMD
Do i Dual core or not dual core
Do i Sli or Crossfire.
What make or board
What ram to use

Want to spend about £700 whats the best route, Mostly gaming and a lot of unrar'ing.

Cheers

 

[semi-pro waster]

For gaming then AMD is definitely the way to go, dual core is handy if you are going to be using multiple applications at once although still not strictly necessary just yet but it is becoming more widespread.

SLi and Crossfire are generally not worth the extra over a single card and especially not on a £700 system.

The other two questions I'll leave for the moment and ask one of my own Is there anything you can/will salvage from your existing PC such as hard drives/optical drives/case/PSU etc to cut down on costs