If there is a language toolbar on the start bar thing, click that. If not, right click the bar, select toolbars, and then choose language bar. When that pops up, click it and you should get the options.
Orrrrr:
Control Panel > Regional and Language settings > Click the languages tab > details. Change it there.
This is all on WindowsXP by the way, it might be slightly different for 98 or something, but there will definitely be something in control panel for it (Y)