Blog export character conversion

I’ve just transferred a blog over from wordpress.com to my own servers using the import/export features. A few of the posts have Vietnamese characters in them, and these characters appear garbled in the new, ‘imported’ blog. I have read up a bit on the utf-8 / latin-1 encoding issues, although I’m not sure this is what is going on. Sorry if I’m wasting time re-asking a question, but I couldn’t find anything that I was sure was addressing this issue. Any ideas?

Here’s a good example of before and after… sorry about the unwieldy link:

The old blog:

http://gastronomy.wordpress.com/2008/02/29/c%c6%a1m-t%e1%ba%a5m-bi-s%c6%b0%e1%bb%9dn-ch%e1%ba%a3-tr%c6%b0%e1%bb%9fng-opla/

The new blog:

http://gastronomyblog.com/2008/02/29/c%c6%a1m-t%e1%ba%a5m-bi-s%c6%b0%e1%bb%9dn-ch%e1%ba%a3-tr%c6%b0%e1%bb%9fng-opla/