I just installed Windows 7 Service Pack 1, and immediately noticed screen flickers every 1-2 seconds.
I have T410 with NVS 3100M, using a HDTV for monitor through a DVI-HDMI cable.
The update may have reset default video settings. Check video control panel for resolution and refresh rates. Confirm the settings, and save / apply / OK and exit.
In this specific case, the solution was to change the resolution under the NVIDIA control panel settings to HD, SD 1080p, 1920 x 1080 (recommended) at 50 Hz refresh and it seems to solve the problem. Previously it was set to PC 1920 x 1080 (native) at 60 Hz refresh.