Easy enough tweak to usually find out about it on your own, but still, some of use still don't find it right away. So here it is:
1: Start > Right Click on My Computer and select properties.
2: Click on the "Advanced" tab
3: See the "Perfomance" section? Click "Settings"
4: Disable all or some of 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.