New Build: Under £500

Hi there,

I'm looking to build a brand new PC for hopefully under £500. I was planning on this including the tower and a standard 19" screen but if you feel this to be unrealistic I shall most likely increase the budget.

I'm looking for a fairly powerful computer, but not at all a high end gaming one. Something that will handle some decent games on maximum graphics at decent FPS, but not Crysis, Assassins Creed, World in Conflict or COD4. It'd be of the Age of Empires games, other RTS's and maybe the Pirates of the Caribbean or X3 series.

I am planning on buying a brand new graphics card for my son's computer allowing me to use his nVidia 8800 GTS 640MB which he has been using for a while and has served him fantastically well. Using that card, I hope to save a fair bit on the price but I would need a compatible Motherboard and suitable PSU of course.

Any advice would be much appreciated,

Thanks again,

Sabre_X