If your chat windows aren't locked, Dorick, you can hover your mouse over the top of your chat window until a tab marked "General" appears; right-click that, and look for "Font Size" in the resulting menu. From there, you can adjust the font in your chat window up to 18 pt (from the default 14 pt). If your chat windows are locked, you can press Escape to enter your In-Game Menu, select "Interface Options," and look for a checkbox marked "Lock Chat Settings." Make certain that's not checked, and you should be good to go. :)
Ce sont ces fenêtres qui m'appellent...