Use 'Shift + Caps lock' instead of 'Caps Lock'

Solution 1:

In autohotkey:

CapsLock::Return
+CapsLock::CapsLock

Though you could then set Capslock itself to a much more useful function rather than disabling it entirely. You could have it equal to shift, for example:

Capslock::Shift

or set it to open/switch to Firefox:

Capslock::
SetTitleMatchMode, 2
IfWinExist, Mozilla Firefox
{
IfWinActive, Mozilla Firefox
{
Send ^t
Send !d
sleep, 100
Send ^a
}
WinActivate
WinWaitActive
}
else
Run %programfiles%\Mozilla Firefox 3.1 Beta 3\firefox.exe
return

(Though the latter would need a tiny bit of configuration for FF's path, and how long you need the sleep to be)

Solution 2:

You can use Autohotkey for this

+CapsLock::CapsLock
CapsLock::return

Solution 3:

The small free application CapsUnlock does this fine.

CapsUnlock supersedes the locking mechanism of the CapsLock key and thus prevents the accidental turning on of CapsLock. It runs as a little tray application in the taskbar. The user can select an override option, which allows CapsLock to be switched on and off by holding down the left Shift key while pressing CapsLock.