it worked!!!!!
apart of that, when i turn one the computer, it says that i still have to install the drivers (and they are already installed 91.31...).
i put the game (oblivion) and the launcher, it says that doesn´t recognize the cards settings, so the program set the resolution to very low.
if i launch the game from the .exe, it works ok and the card seems to work too. but not really much improvement from x1900xtx (at 700mhz core, 850mhz memory). and i´m running on 1920x1200 that it´s where this cards take the advantage.
maybe the drivers are not good yet (the new mode from nvidia control pannel restart the computer).
i hope they improve soon
PD. i wond what do i need to play oblivion the way i want (xfx 7950 xxx, fx-57 at 3´1mhz, 2gb ocz ddr at 530mhz, serial sata 2,...)