Firstly, forget the driver! not needed. They do supply a driver but it is not necessary. What you need to do to tell the video driver (which will not have changed) that you want to drive a different resolution.
This is what to do....
Right click on desktop somewehere away from any icons and chose "Properties"
Click on "Settings" tab
There is a Screen Reslution slider there - can you see the mive the slider to the required resaolution (1440 x 900)? If so, move it to that and click Apply and see if the display is as needed.
If 1440x900 is not there, carry on process below.....
Click on "Advanced" button
Click in "Monitor" tab
In Monitor Type - what does is say? hopefully Acer1916W, biut if not no worries
The option 'Hide modes that this monitor cannot display' is probably checked - uncheck this
Click on and you will be taken back to Settings tab and the slider will now show a lot more little marks
Now move it around and you will find almost certainly a 1440x900 option
Select that and click OK (make sure you do OK, not Apply!)
The resolution will change and a message will come up saying something like "The Desktop has been reconfigured. Do you want to save these settings?" - If it looks ok, Say yes - If you CANNOT ready anything, then after 15 seconds it will revery to as it was
(this is why you didn't do APPLY - as the apply will not automatically go back if you cannot read the message)
After following this process, you will have your new moinitor running at 1440 x 900 and it will look great!!
If it doesn't work, PM me and I will try and see what the problem could be (after suggesting that screen, I will responsible for making sure it works!!)
Good Luck and let us know if it works

I went to a bookstore and asked the saleswoman, "Where's the self-help section?"
She said if she told me, it would defeat the purpose.