Trapz101 makes a good point about proper style/form.
See a few people wearing a lifting belt, though the belt thing seems to come and go over the years. Do whatever you believe is best for you. Some will cinch up the buckles to draw in the waist and give the illusion of a "V" taper their whole time in the gym...not that BB'ers are vain or anything like that.
A well designed belt can act as a semi brace, if wore the right way, and assist in lifts. Some more expensive belts are custom made, for the most part, to fit the curve of the lower back/spine and obliques and are measured for the proper height......assuring proper support. If you do have a belt that you like (but not custom made) than might suggest putting a folded up towel against the lower back and the belt, to whatever thickness you wish, and tighten it up that way. Can give much better support for most guy's.
Lifting belts, in serious training, are usually only required for lower rep efforts; like 1 to 3 reps. . Lifting belts, to get the most out of them, need to be extremely tight, which in return can cause cutting off of blood circulation and impaired breathing. A few lifters have blacked out from this affect. May also raise the the blood pressure to a higher degree.
Working the ab's strongly, with added weight and lower reps, can do much to assist the all around strength of the lower back. If guy's worked the ab's as strongly as the back, belts may be a thing of the past. But than agin, that would be personal choice for you. Good Luck.