How to type Chinese with my computer?

This is just based on my own experience. I use Windows XP so I guess for Vista it is slightly similar...

Initially, you are using French or English Windows. The oriental languages are not activated yet. If you want to be able to type these (Chinese, Korean, Japanese, Thai etc...) just go in Configuration Panel (Panneau de Configuration) then choose Regional Options, Language, Time, etc... (Options Régionales et Linguistiques).

A new window open, now click on "Languages" and tick the two boxes "Install the file for the complex script languages...." and the second one.
You need to insert your CD of Windows because the language files needed may not be on your hard disk yet.

Just reboot the computer, and TADAAA! you ALMOST got it :)

Go back to Regional options and languages (Options Régionales et Linguistiques), click on "Languages" (Langues) and click on "Details" (Détails) lol.

A new box appears showing the main language used for the computer and other available. Click on Add and choose Chinese of any language you want.

More specifically, for Chinese, I really like the QuanPin input system. It's the smartest for those who want to use pinYin.

After choosing, click Apply, and OK. Now you can type it. You need to choose Chinese.

Useful tips: press "ALT and Shift" to change language and conveniently switch between two keyboards.
(When you type PinYin you're actually based on a QWERTY keyboard and not an AZERTY one.)

Good luck! ;)