Title explains it all. I'm setting up a new laptop and noticed some of the icons look like crap and are blurry/jagged. Laptop is at native resolution, and the taskbar icons are the only ones that appear to be doing this.
The problem is a combination of a some-what-lower native resolution and the icon itself. There nothing you can do about it.
The example below is from my computer. My resolution is set at 1920x1080 (native). Since the resolution is higher, it makes the icon smaller on screen. It's the same effect you get when you zoom in on a picture.
It's also possible that you are using Windows 7's display setting too. I have my profile set on the smallest. However, when I switched to Medium, the default, I was able to recreate the jaggedness.
Adjust the size of text and other item on your screen
Note: You must log out of your account then back in before it takes effect.