If you're looking to get the most out of Windows, you should master some of the many keyboard shortcuts that are available. These are all specifically based around the Windows Key, which appears on newer PC keyboards:
Quick Launch shortcuts
Shortcut: WinKey + 1, 2, 3 ... etc.
If you use the Quick Launch taskbar toolbar, you can quickly launch up to the first nine shortcuts you keep there using the Windows Key plus a number. So the first shortcut, from left to right, would be WinKey + 1, the second is WinKey + 2, and so on.
Show desktop
Shortcut: WinKey + D
This one hides everything to get you to the desktop, including Windows Sidebar.
Minimize all windows
Shortcut: WinKey + M
This one is subtly different from "Show Desktop." With Show Desktop, the Sidebar is hidden as well, whereas WinKey + M minimizes all active windows ... but not the Sidebar.
Windows Flip 3D
Shortcut: WinKey + Tab
Most people are probably familiar with Windows Flip (Alt + Tab) but you can also enable Windows Flip 3D via the keyboard as well.
New Explorer window
Shortcut: WinKey + E
More shortcuts
Jason C. notes via email that Microsoft maintains a full list of Windows Vista keyboard shortcuts. You can find that list here.