Can I use my oven for sous-vide
Accuracy of the temperature is going to vary by oven, so there's no definitive answer there. As GdD said, you'll just have to get a thermometer and try it. 

However, I think this will probably work fine for most sous vide applications. While sous vide is all about precision, a couple of degrees fluctuation isn't going to make a huge difference for most preparations (eggs are a notable exception), particularly given the thermal mass of the water. You could also throw a pizza stone or something in the oven too to help keep a more constant temp.