Yeah you're right, I just wanted to be sure you didn't maybe make a change to the display hardware.
Have you tried viewing a high quality video (local video/video disc) using say Cyberlink, or even WMP or VLC? Can you see the same noise in the image, or only when streaming?
I've seen similar issues but you're not using old VGA junk
Windows 7 is certainly capable as well as the GTX260. Great Gpu for its time, and packs the necessary goods in the driver package as well. There are others here who may have more experience or have seen this before, msyelf I've only seen it as result of a hardware issue, straight forward.