Jay, commenting on my blog entry for 24 March (Unicode Phonetic Keyboard), mentioned that Windows Vista also has an on-screen keyboard. You find it by going to All Programs | Accessories | Ease of Access | On-Screen Keyboard.
The display is context-sensitive. If you install and engage Mark Huckvale’s Unicode Phonetic Keyboard and then launch the on-screen keyboard you see this:
(It’s about half as big again as shown here.)
If you click on Shift, the display changes to
Click on the righthand Alt (actually called AltGr on a UK keyboard), and you get
Clicking on one of the virtual keys on the on-screen keyboard has the same effect as typing the key itself. This constitutes a very convenient way of entering phonetic symbols.