What I find funny/wierd/stupid....
There are two ways to make thai characters available on a webpage:
1) Set the charset (code behind)
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Response.Charset = "tis-620"
2) In the meta tag (html)
meta http-equiv="Content-Type" content="text/html; charset=windows-874">
This should do the same, AFAIK, but it seems it dont. When i do 1) and make a form and submit that form, the characters get messed up. When I do 2) all works well.
So you really need to do 2) and then use the right collation and insert statement to insert into you database. I think that it is funny/wierd/stupid that there is difference between 1) and 2)