The Blue Purple style actually bother snakes more, and do not put out much heat.
IR bulbs put out a wavelength of light that is nearly invisible to snakes. (even people can look almost straight into them without thinking that they are bright.
IR bulbs over regular red bulbs because IR heats better.
I like these work the best: http://www.petsmart.com/product/inde...uctId=11147193
I suggest a 75 watt or a 100 watt if your lamp can handle it and you get a dimmer ($15 at Walmart or home depot