Or you could wait to buy the Rosetta Stone once you get to Thailand....that would be MUCH cheaper!
It's quite an intuitive method, much more like the way children learn languages...might suit you if you are not very keen on conjugating verbs etc.
This said if you're only going to be here for two months and in Phuket then you won't really need to learn Thai...maybe just get some basic everyday phrases and learn the numbers like most foreigners do. Learning sufficient Thai to understand TV news and newspapers is a bit ambitious IMO!