Ok.... here is the answer for those that haven't found it.
I am using a solution from the Sweetwheels user post, but it IS the answer to Simpleviewer v2 not showing up in IE.
If you paste the <object... code from the "basic_embed.html" file, it WILL work in Firefox, BUT it will just show up as an indented box with nothing in it while looking from Internet Explorer.
HERE IS THE SOLUTION!
Use this code in the <head> of your page....
<script type="text/javascript" src="swfobject.js"></script>
<script type="text/javascript">
var flashvars = {};
flashvars.galleryURL="gallery.xml";
var params={};
params.allowfullscreen="true";
params.allowscriptaccess="always";
params.wmode="transparent";
swfobject.embedSWF("simpleviewer.swf", "flashContent", "700px", "600px", "9.0.124", false, flashvars, params);
</script>
(You can change the "700" and "600" to fit the size you are wanting it to fill. Also, you can take out the params.wmode="transparent"; line if you want it NOT to be transparent. Otherwise, it will be from my code.)
You are not finished yet, though.
COPY THE NEXT LINE where you want the Simpleviewer to show up on your page.
<span id="flashContent"></span>
The creator of Simpleviewer put a line that tells people to download the latest Flash player if the viewer isn't showing. I might add that later, but I can attest that the shown solution WILL fix your problem of the viewer not showing in IE if the symptoms are the same as above.
Make sure that you are using all files from Simpleviewer v2 for it to work.