Weight lifting belts vs Power Lifting belts, which do I need?

[IrishLuck]

I've posted regarding this before but got little help.

I've never used a belt...but recently my squats/deads are getting pretty good...and high enough that I think I should be using a belt for my 1RM.

People have said get a power lifting belt...is that necessary?

And what's the biggest different (besides size) of these two?

http://www.bodybuilding.com/store/sck/2006.html
http://www.bodytrends.com/store/prod...y_Code=BT01-15

I'll spend 50 if I need to.....as you only get one back. But why do people get powerlifting belts as oppposed to regular belts and why do people get regular belts as opposed to powerlifting belts?

Also, what does a 4 3/4 belt do that a 6 inch belt doesn't? That's the difference between the 2004 and 2006 models.

Finally, is Schiek a good brand?