Need someone very familiar with Outlook Express and HTML

I have a Dimension 9100 running WinXP Pro SP2. I need some help from someone that really knows the ins and outs of Outlook Express. Here's the problem.

 

I do graphics and I insert them into my email when I send them out. However, I was doing the HTML email on my 8400, which just was sent back to Dell because of numberous hardware problems. Now I'm using a 9100. I have been trying to insert HTML code into email for several hours now, with no success. I know that the HTML code I am using is correct because I can use it on websites. However, something is blocking the code that goes in the email. I checked everything. The firewall, Norton Antivirus, the HTML settings. You name it, I've tried it. Does anybody have an idea of what could be blocking the code from going into the email? Well, it goes into the email, but when I click on Preview, all I get is a red X. It's very frustrating. Any help is grateful.