Before I look about for something for you a few questions.
What graphics do you have and what is the model number of the widescreen monitor you have?
I just want to make sure that you have been told the truth by checking out the resolutions of both myself.
Also does the graphics card you have do all you ask of it or do you need an upgrade anyway?
Does it really matter if you run the monitor at a slightly lower resolution, I do it with mine, mainly because when gaming I find the optimum resolution for my monitor makes the graphics card struggle a little bit.
And finally, assumming all other questions have been answered, how much are you willing to spend and what is the spec ie speed of your PC?