Thailand has its own written languages. These are easily made available on the World Wide Web. The important thing is just to download some fonts. These are made available by NECTEC, the technology organisation for Thailand. The main fonts are 'DB Thai Text' and 'DBX Thai Text'

Once installed, check whether your browser correctly displays the Thai language pages from The Nation. Please select the fixed width font.

DB Thai Text is appropriate.

Thai Font Resources
Excellent Technical Notes
Configure Thai for Your Machine
Thai Pages From The Nation
Get from NECTEC