i would like spend about 100€. And good resolution if its possible with 1920x1080 but my computer is old and i thinik that couldn't be.
Thank you for the answers!
You can get a Radeon 7750 for 110 US dollars or if you like nVIDIA (like me) you could get a GTX 550 Ti for 135 dollars. The 550 Ti is slightly better than the 7750. With either of the cards you should be able to play most games at decent settings. Find out your native monitor resolution, if it's lower than 1080p then go for the cheaper 7750 card and spend the money leftover to buy some more good ram.