The brand new Nvidia and ATI cards are INSANELY Expensive right now. you might want to take a look at the 9000 series instead. The 9800s are down to around 100 euros if you find them in the right place. You're going to want at least 2gb, perferably 4gb of ddr2 memory, which has become pretty cheap lately. Kingston, patriot, and corsair all make good memory. The best hard drives imo are western digital and Seagate, both are long time makers and have their stuff down.
You only need a dual core for gaming, even intense stuff like 3d modeling, movie editing and the like you dont need a quad core for. You certainly do not need an extreme edition, they are still very expensive and overpriced. I have a quad core, and it's amazing, however it's really only useful for things like compiling code, running large database commands, and encoding video. Most stuff doesn't really support quad cores yet, very very few games are designed for quad core and only a handful for multicore at all.
As far as a motherboard goes, XFX and EVGA rule. Foxconn and asus are also pretty good. If you're really into gaming i would definetely suggest an XFX or EVGA board though. Remember if you're gonna be doing intensive stuff to get good cooling, that includes THE CASE, as well as looking at better heatsinks than stock. Make sure that case has alot of fans on it. The worst thing you can do is fry parts a few days after you buy them cause something overheated.
