center page in browser and fix rollovers in FF

I am new to CSS and I am having trouble getting my page to center in the browser and get my rollovers to position correctly in FF. I really could use some help.


here is the link http://dev.kleidon.com/portfolio_home.asp

In my css I have

html, body {  
	/*background-image: url(../images/KA_WebFinal.jpg);	
	background-repeat: no-repeat;*/	
	background-color: #000000;	
	margin: 0;
	padding: 0;	
} 

#wrap {		
	margin: 0 auto;	
	width: 800px;
	height: 512px;			
}

.portfolio_menu {
	position: absolute;
	top: 50px;
	left: 12px;	
}

.grid_image {
	position: absolute;
	top: 106px;
	left: 335px;
	z-index: 5;		
}

.logo_image {
	position: absolute;
	top: 403px;
	left: 12px;	
}

HTML:

 

how do you want to center it??
horizontally or vertically?

 

Check out Rollover trouble for some roll over information and Centering in Firefox on centering

 

wasabi, I need it centered left to right, align top so horizontally?

Thanks for the other thread links, I'll check them out.

 

Ok, I tried the suggestions that the links had and now my page is all whacked out. Here is my style sheet.

--edited 857am ----
I managed to center everything except on FF my rollovers are still messed up here is what I have so far.

html, body {  
	/*background-image: url(../images/KA_WebFinal.jpg);	
	background-repeat: no-repeat;*/	
	background-color: #000000;	
	margin: 0px;
	padding: 0px;	
} 

#wrap {		
	position: relative;/**/
	margin: 0 auto;	
	width: 800px;
	height: 512px;	
	/*text-align: center;*/			
}

.portfolio_menu {
	/*position: relative;*/
	position: absolute;
	top: 50px;
	left: 12px;	
}

.grid_image {
	/*position: relative;*/
	position: absolute;
	top: 106px;
	left: 335px;
	z-index: 5;		
}

.logo_image {
	/*position: relative;*/
	position: absolute;
	top: 403px;
	left: 12px;	
}

Code (markup):

 

I think I got it working. I had to make a new class for the image rollover to work right in FF.