Windows 7: Problem in Adjusting Screen Resolution

Hey Friends,
I have Samsung Sync 15000:1 19' inch LCD Monitor with Native Resolution of 1600x900 & Windows 7 is installed in my PC.
Last time i was playing GTA & Suddenly PC Switched off Automatically due to Power cut.
After that i started PC & saw that 1600x900 Resolution is going out of screen.... & i cant even Adjust it through Monitor Buttons!!!
I Tried System Restore but even that didnt Helped
I changed Graphic Card of NVidea 9400GT to GeForce 7025 & yet 1600x900 is going out of screen
& now only 1280x1024 Resolution can be adjusted to see everything Properly........ But its not as sharp as 1600x900 was
i want that back!!! Can anyone tell me Solution?????
Even Re Installing Graphic Drivers Didn't Help me!!

Do you have the latest drivers for your monitor installed?

yes

try doing a repair install and see if this doesnt fix it... Repair Install

i think i should keep this step Secondary
i mean if there is no other Option
this what i will have to do........ but till then let me see any other solution........
anyways thanx.........