LifeinAsia - 3:22 pm on Jun 8, 2010 (gmt 0)
Assuming you want them to buy, you need to translate the entire buying/checkout system, including all your refund/cancellation policies. You'll also need to translate one or more landing pages- the number depends on your budget.
Forget about using machine translation- it's a joke, makes you look cheap, and therefore lowers trust in you from potential customers. The best situation is if you can find a translator who understands SEO and can translate your pages with keyword rich translations.
Also, remember that translating the site is only part of the equation. The other part is customer service- how are you going to respond to those Japanese and Chinese customers when they write/call you with problems/questions in their native language?