Well, you should check the requirements of the programs you want to use. Some graphics programs need pro level cards, so if your software requires one of these cards then you'll want to drop the extra money on the Quadro. In terms of sheer speed and power, the 5000 won't hold a candle to a 690. It's two generations older and just doesn't pack the same horsepower as a 690. Quadro cards aren't built with gamers in mind, anyway. There are some hardware differences between gamer and pro level cards but the biggest change is the driver, which is optimized for professional graphics programs and not games.
Here's a good article about what you can expect from a 5000:http://www.xbitlabs.com/articles/graphics/display/nvidia-quadro-5000_2.html#sect0
Bottom line: check your software's requirements and buy accordingly!