IE & Safari vs. Firefox display issues

I’m having a bit of a problem getting my layers to display correctly among the different browsers…particularly trying to set a horizontal position. This’s the problem page:

http://www.cercajewelry.com/pages/index.html

There’s about a 25px discrepancy between the way IE displays them and the way Firefox displays them. Safari’s display has been close enough to IE that I don’t see it as too much of a problem. Right now, the margins are set so things look the way they’re supposed to in IE.

Is there any way around this? Is it a problem with the code? Any pointer in the right direction would be greatly appreciated.

Thanks!