Download it and put it on your desktop, or in a folder somewhere.
Then open display properties and click on the monitor tab. Then Properties and then driver. It should give you the option to update driver. Click on it and point it to where you placed the downloaded driver. Once it's done, you can delete the downloaded file.
Please note, I'm on Vista, so I am going on memory as to how it done on XP. Some of the info may not be exact or may be missing a step or two. But anyway, that should get you far enough to find the exact tabs you need to click on to get to the driver update page for your monitor.
However, my guess is that it's a graphics card driver issue, not the monitor driver. It probably won't hurt to undate the monitor driver though.
Does your monitor show up as a Acer X223w or does it say Default monitor?
Hope this helps