The live thumbnail view when you hover over the icons on your taskbar is a very nifty feature, and is very handy. I use it very frequenty to get to the window and browser tab that I need right away. But, for those that want larger thumbnails than what Microsoft offers, here’s how.
1. Open regedit (Start > type regedit and press enter)
2. Navigate to HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionExplorerTaskband
3. Create a new DWORD (32-bit) and name it MinThumbSizePx
4. Change the value to the size in pixels that you want your thumbnail to be (use the Decimal value). I used 400.
5. Restart the computer (or log off and log back in). Start a program, and hover over the icon on your taskbar. Larger thumbnail!