The GTX260 is not capable of DX10.1, just DX10. Your OS may have updated the software to 10.1 but only Radeon 4000/5000 or Geforce 210/220/240 cards are capable.
However the latest is DX11 and the HD 5770 is only a little slower than the GTX260, $30 cheaper, has DX11, and much lower power consumption/noise.
Otherwise the 4890 is essentially the same price as a GTX260 but a little faster (about the same as a GTX275) and supports DX10.1.
However the latest is DX11 and the HD 5770 is only a little slower than the GTX260, $30 cheaper, has DX11, and much lower power consumption/noise.
Otherwise the 4890 is essentially the same price as a GTX260 but a little faster (about the same as a GTX275) and supports DX10.1.