Simple top banner height question. Options

[aaazAZ09]

I'm trying to design my band's layout, and I currently have this top banner code ("<" marks changed to "[" for this post):

[div style="width: 855px; height: 275px; z-index: 1; position: absolute !important; margin-left: -421px; left: 50%; top: 174px !important; border-width:0px;"]
[img src="IMAGE URL" border="0" /]

The banner is beneath the navigation bar and ad. This code has worked fine for me for about a year, but I've been wanting to make a taller banner for a while. Every time I try and do this, it always ends up bleeding into the artist name, artist picture, and music player. What can I change in this code to fix this?

Thanks a lot guys!

Edited to add: I've also tried using the top banner code in the band layout tutorial, but it didn't work for me, and I don't really want to have to redo my entire layout.