depends on games but in a lot of games you will be bottle-necked
It is because the core itself in the E5700 is weak
bottleneck is when you have a part in your PC that is much weaker than the other parts , it will become bottleneck
(data passes really slow through it ) so when you game your performance will be measured by your weakest part which is your CPU
This CPU is just un capable of feeding the GPU with enough data
games may or may not be able to work well
Depends on the game itself
What games do you plan to play and how much FPS do you expect ?
Also are your Motherboard PCI-E or AGP ?
because if it is an AGP motherboard 260x can't be installed in an AGP motherboard