Would like some help speccing a computer

[UnknownSoldier]

I have been out of the hardware loop for about 2 years now so I am not really sure what is good and what isnt(been using a laptop) but I think I may go back to desktop for the performance.

I use my computer for games, image editing, video editing etc.

I am thinking of spending around 600 quid (ex monitor + speakers) and I would be fine with overclocking the components. Any suggestions? Looks like I should go for Intel + AMD at the moment?

 

[UnknownSoldier]

What about the Intel Pentium 4 805 Dual Core "LGA775 Smithfield" 2.66GHz that seems to clock really well, is dual core and costs 80 quid?

Also what is the difference between the Conroe and Allendale cores?