Easy enough tweak to usually find out about it on your own, but still, some of us still don't find it right away. So here it is:
Start > right-click on My Computer and select Properties.
Click on the "Advanced" tab.
See the "Performance" section? Click "Settings".
Disable the following:
Fade or slide menus into view
Fade or slide ToolTips into view
Fade out menu items after clicking
Show Shadows under menus
Slide open combo boxes
Slide taskbar buttons
Use a background image for each folder type
Use common tasks in folders
There, now Windows will still look nice and perform faster.