Thai wordprocessor on XP?

We have finally scored a Thai keyboard,

and need to set up (perhaps Messenger?)

so my wife can talk to her family in Bangkok.

Any suggestions from anyone who currently does this?

In my old Win98se I used a small program

called "ThaiKbrd.exe" IIRC.

I am new to XP and would welcome

any detailed explanation on a suitable set up

Thanks

Rodney