Just to step through a few of the biggest problem areas:
Complete doctype and character encoding like this:
You can only use an id once. That first one could be renamed #header maybe.
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<TITLE>PowerOverWireless.com - Home</TITLE>
The second #wrapper needs the floats cleared.
I usually use a strict doctype that requires you to close things.
<DIV id=headercolumn1><A href="http://www.poweroverwireless.com/"><IMG height=65
alt="Power Over Wireless" src="power_files/logos7.png" width=564 border=0></A>
I THINK that html 4.01 lets you do it this way, but I'm not sure... I'm used to adding a </li> to close each list item.
When you resize the site narrow enough, the content in each column breaks out the bottom. Need to figure out how you want to handle that, overflow: auto; maybe?
<LI><A tabIndex=1 href="http://www.poweroverwireless.com/">Home</A>
<LI><A tabIndex=2 href="http://www.poweroverwireless.com/power.html">Power</A>
There is so much stuff in #resourcebox that I lost count of the divs!
I think there was one that was not closed though? Check the validator for that.
To get a box around your 3 columns at the bottom just have #resourcebox enclose #resourceheader and #resourcecolumn1 through 3.