My normal rule when buying graphics cards is to look for a good card around the €200 mark with extra graphics ram if possible. Such cards generally offer excellent performance for the money while the additional memory helps a lot with longevity. Today however I have just ordered a card costing closer to €100 than €200 and it has the same 1 Gb of graphics ram as my existing 4850.
What happened to cause me to break my own rule? The Sapphire Radeon 5850 Extreme happened. The 5850 is actually a high end card from last year that would have set you back some €250 in its day but it has been superseded by-newer shinier cards in the meantime. Sapphire however have pulled a master-stroke and have released a limited edition of the 5850 with a great low noise cooler for a give-away price. This card easily outperforms later generation cards like the Nvidia 460 and ATI 6850 that cost 50% more.
What do you lose by not buying a more up to date card? Well the later ATI cards support some form of 3D display a feature I am unlikely to ever need and of course you eschew PhysX support if you don't buy an Nvidia card. If you can live with those minor limitations then this is an outstanding graphics card bargain.