On screen keyboard

Instead of relying on the physical keyboard to type and enter data, you can use On-Screen Keyboard. On-Screen Keyboard displays a visual keyboard with all the standard keys. You can select keys using the mouse or another pointing device, or you can use a single key or group of keys to cycle through the keys on the screen.

To type without using the keyboard
Open On-Screen Keyboard by clicking the Start button , clicking All Programs, clicking Accessories, clicking Ease of Access, and then clicking On-Screen Keyboard.

Basically, it messes up key stroke logging.

Go on, ask what that is...

Keystroke logging (more often called keylogging or "keyloggers") is the action of tracking (or logging) the keys struck on a keyboard, typically in a covert manner so that the person using the keyboard is unaware that their actions are being monitored. There are numerous keylogging methods, ranging from hardware and software-based approaches to electromagnetic and acoustic analysis.

Definitely the method of choice when typing passwords!