The font "Phonetic" (this is the one I use: it combines regular characters and funny phonetic symbols so you don't have to switch fonts). Download the 4 files to your desktop (or, at least, the first file) and install them (Contral Panel - Fonts, then there's an install new font option). Or, under XP, if you can locate the font folder, drag the files to the font folder.

A list of the characters in the Phonetic font. plus the keystroke sequences relevant for Accent Composer, q.v.

The SIL IPA font (this program installs the fonts).

A list of the characters in the SIL IPA font.

Accent composer. This is an extremely handy typing utility that allows you to enter any character in a user-definable manner. I highly recommend it. This version expires in 30 days from installation or 15 uses, and it costs $25 to buy. I also have a preset translation table with reasonably mnemonic sequences like (tap right ctrl key plus) ae gives you the character æ.

The Accent composer utility. Click this, which is a zip file of Accent Composer. Download and unzip it into some folder; then open the folder and start the program ACompose. You get 30 days free use, and I think the first time it opens the help window which you can close. It put an accented A icon in the lower right corner, and if you click it you can fiddle with the options. Some useful options to fiddle with are: (a) check "load at startup", (b) you can assign the "tap" key to e.g. right-alt or right-ctrl or other things and (c) if you import silac.dat, that gives you some predefined key sequences for both the SIL and my Phonetic font. You can read the file silac.dat to see what's what. Here's how I have it set up. I tap (press and release) the right ctrl key, then press s9 and I get the SIL `ayn character.