New desktop computer

I just found out today that i won't be able to play civilization V when it gets out next week, because my computer is too outdated (http://img299.imageshack.us/f/specsc.jpg), but it's around 6 years old, so it's not really surprising. It didn't take me long to find out that my knowledge of hardware parts is outdated as well :P So i would be glad if any one could come with some suggestions/ help me pinpoint in which direction i should look.
I mainly use the computer for browsing, email and gaming (gw, rpgs and strategy games), sometimes a little photo and video-editing, but nothing the old computer couldn't handle.
I prefer to buy good quality and use it for a long time, over buying some cheap crap that only last a year, so i would like to get a computer there also can handle new games well in 3-4 years. My budget is around 7000 dkk (~1250$), but if it takes more to get a proper gaming computer, then that's how it is ;-)
I guess i can find a HDD to use for storage, but i would like a small SSD (somewhere between 60 and 128 gb) for the OS and programs. And USB 3.0 would also be very nice, unless its unreasonably high priced?
I don't mind assembling the parts myself, nor waiting a few months, if there is something especially fantastic soon to released.

Couple quick questions:

Where do you plan to buy parts?

Do you need a new monitor/mouse/keyboard/OS as well?

I don't have any specific sites in mind, but either a European or danish website, depending on the prices and delivery rates.

Already have mouse and keyboard, so don't need those.
The monitor is even older (it's a professional "flat screen" from back when they were almost unheard off ;-), but it function flawless so ill stick with it, unless it comes as a bundle. The same with the OS i have a xp license somewhere, so unless win7 is either bundled or very cheap, then ill stick with that xp.