I work on webpages involving Non-English scripts from time to time, most of them uses utf-8 charset, VIM and Gvim does not display UTF-8 Characters correctly.
Using
On Microsoft Windows, gvim wouldn't allow you to select non-monospaced fonts. Unfortunately Latha is a non-monospaced font.
There is a hack way to make it happen: Using FontForge (you can download Windows binary from http://www.geocities.jp/meir000/fontforge/) to edit the Latha.ttf and mark it as a monospaced font. Doing like this:
Good luck!