tips on purchase
a tip on buying these lights - ONLINE. pet stores typically charge upwards of $30 for Reptisun

and you can get them online for as low as $14
www.reptiledepot.com (good price, but can be slow on shipping in my experience)
www.lllreptile.com has them for $13.99 all sizes

(I have found their service on supplies to be good)
and there are others. I would also suggest getting a few (at least, and take advantage of sales to save on shipping) at a time since you have to replace them a couple times a year. Also keep in mind that all fluorescent lights lose their strength at either end first and rapidly. So a 4' bulb is really giving you 3' of light/UVB (approx6" of loss each end).
Another tip is to use a permanent marker to write the date on the end of bulb the day put it in service so you can keep track of when to change.
I have not read the thread that Brad wrote (sorry) so if I have repeated anything, my apologies

lele
p.s. I agree on using the ReptiSun 5.0 for whatever that is worth...