It will fit, yes. But if you have the stock 250W power supply, there's not enough power there to drive it under load. Heavy use like Gaming will likely cause your system to shut down. Use this PSU calc to estimate the size PSU you need.http://www.thermaltake.outervision.com/
One other thing. The GTX 560Ti cards come in various lengths. Most are about 9 1/2", but some are longer. You may want to find the length of the card you are interested in and measure inside your case to be sure there are no unforseen obstructions. A HDD cage may sit to close to the back of the card. Or some other obstruction.