There are more than one type of malaria treatment widely available, from Mefloquine to the newer Malarone, which only requires you to take tablets 3 days after you return. Costs vary, but you should have been advised to start a course of prophylaxis early, so any side effects can be monitored and the medication changed if needs be. Have a chat to a pharmacist, or your GP. If not, organise this NOW.
I've spent 5 weeks working out in Tanzania, which has a 'serious risk' of malarial illness. You CANNOT wait until you are in Thailand as you must build up an immunity. The stories you hear are probably 'mates tales'- I've certainly never seen such things happen. There are mosquito repellants widely available- they actually block the smells the mosquitos sense you with to effectively make yourself invisible. Stores such as Blacks and Millets also offer anti mosquito lights and the like; there's a huge range of products widely available and I'd strongly advise you check them out. Buying a mossie net to sleep under may also be needed, but I don't know where you plan on sleeping. Only wear skin baring clothing when necessary!
If you follow travel advice and act prudently, there's a relatively small risk to you, but you cannot afford to be complacent. I always carried a small amount of Quinine just in case, but after 5 weeks in a country with the second highest infection rate, I was fine, so enjoy your holiday!
Hospital for Tropical Diseases:
http://www.thehtd.org/travel/destination.asp?D ocID=181