Centering in CSS

[NJCarrier]

This is my first experience with CSS. I started with an open template and made lots of modifications, so my knowledge in CSS isn't the greatest. I would like to set the page width as a percentage (perhaps 95% or so), but don't know how. Here is the applicable CSS (it won't let me post the link, let me know if you need more data):

#vertinav {
background-color:#D7D7D7;
width:182px;
height:100%;
float:left;
}

#vertinav ul {
list-style: none;
display:inline;
}
#vertinav li a{
margin:0 0 0 5px;
color:#666666;
text-decoration:none;
}

#vertinav li a:hover {
color: #00007c;
}
.vertinavheader {
font-size:22px;
color:#000000;
margin-left: 5px;
}


#vertinavcontent {
margin-left:5px;
color:#666666;
font-family:Arial, Helvetica, sans-serif;
}

#content {
background-color:#E4E4E4;
float:left;
width:810px;
}


As it is, it displays fine in FF and Chrome, but in IE the content bar drops below the side bar. I want them to always be side by side. Is there a way to do this?

Thanks a ton!

Nate