http://www.yourhtmlsource.com/access...m404error.html

Your 404 page is pionted to by your .htaccess file, which is just a text document in your root folder - I think it is called 'docs'. It has the URI of your "404.html" in it, like this:And the linked page here shows all about it.

Some hosts, but I don't know ipowerweb, have an online control panel that you use to edit the .htaccess.
Otherwise, you would use FTP to upload the documents from your hard drivw.
And yes, I am pretty sure that you can have images. The 404.html is regular webpage construction (ooh boy !).

Actually, I just visited the ipower site, and if I was at the right one, they use a Windows server.
I am on readyhosting, which is windows, and I have to put in a 'ticket' to request a 404 page. But ipower has a control panel for online browser management, means that you just use Internet Explorer (etc.) to log in and access your site.
So you may have to contact them directly or use your control panel to find out more.
Good luck, keep us informed. :O)