+1 on too small of an enclosure.
Petco is having their $1 per gallon fish tank sale, so there is an opportunity to get a new tank for about used prices.
Nearly everyone on here disagrees with the use of glass aquariums for a means of housing.
(They lose heat, 100% percent visable from all sides, doesn't hold humidity, etc)
I have used tanks, and
IF modified appropriately, they work fine for certain species. (in reference to what Sharthun said above about covering the screen lid)
You can also use a rubbermaid tub for a lot cheaper, but you won't be able to enjoy viewing you ball python, although they tend to hide all the time anyway
Also, if its the heat pad that comes with the starter kit - toss it and buy a new heat pad. I bought the kit awhile back becuase it was cheaper to get the whole thing for a few of the things I wanted/needed. Heat mat never went above 80*F and that was running it WOT (wide open throttle, or full blast, for you non-petrolhead folks)