GT? GTX? GSO? What's the difference?

9500GT would be fine for your needs, look for one with 2 DVI outs, seeing as how you are running dual monitors. Because you don't game, anything above the 9500GT would not benefit you, the 9500 will do anything you require, such as blu ray playback etc.

To answer your original question, the 9600GSO is a G92 core (if you get the right one) that has been disabled, and some of the ram removed, ( although some versions haved added ram such as 768mb flavours ) It is a decent card that is useful for mid level gaming. I bought one for my brother's mild gaming rig. I also bought a 9500GT for my parents computer, so I have some hands on experience with these cards. The 250GTX is a refresh of the 9800GTX+ which was a 55nm refresh of the 9800GTX which was a refresh of the 8800GTS 512, sounds confusing ? It is, Nvidia is very tricky in their naming schemes.

Long story short, the 9500GT is good for you, and cheap, find one with two DVI, or maybe there are some with DVI and an HDMI, also you can buy silent ones, that are noisless which I recommend, I know Sparkle makes one. Good luck!