To run 1680×1050 resolution (which is typical of 20″ and 22″ LCDs) on your Windows 7, you will need to connect your LCD via an HDMI/DVI cable.
Windows 7 doesn’t support 1680×1050 without a digital connection, meaning a VGA connection won’t get you the native resolution of your LCD even if you install the drivers. (This is only in Windows 7, XP and Vista supports it on analog too.)
If you don’t have HDMI/DVI outputs on your computer, get an aftermarket graphic card such as Nvidia GeForce 9800. (that is the only way if you want to run Windows 7)
Of course, your LCD monitor must have either a HDMI or DVI input, most have DVI so…
Once you got those digital connections going, you should see an option in Windows 7 to be able to set the screen resolution to the monitor’s native resolution. Yey, problem solved!