A quality 500W PSU is all that system needs. I prefer Antec, but Corsair, Seasonic, PC Power & Cooling, and Enermax also make quality PSUs. Look for one that is 80+ certified (I believe all PSUs sold in Europe must have Active PFC...true?). You should be able to find an Antec Earthwatts 500W well within your budget. If you want more headroom (e.g. if you plan to run two graphics cards some day), then get the Earthwatts 650W model. Antec's TruePower New line (550W, 650W, 750W) are a step up in quality, and may be within your budget. They are also semi-modular.