Display Issue Firefox vs. Internet Explorer

I just added an Amazon ad in my sidebar (I’m using the default theme), and to give a small space between it and the item before it, I used two <br> commands. This works fine in both Firefox and Opera and gives me the needed space break, but in Internet Explorer the <br>s don’t seem to get recognized. Do I need to do something specific for IE to insert this white space? Any help would be much appreciated.

— Paul