Ya I don't think you are going to have much luck here...
The white sace you see on the left isn't from your website its from the mlsfinder website. Hence if you don't have control over that website, getting ride of that space is not going to possible.
Also, because of this, if you don't want to make your site any wider, you are not going to fit the iframe in.
Unless you control mlsfinder, the only options is to make your website smaller or pop open a new window or present the iframe in a javascript popup box like fancybox...
Sorry to bring bad news.
EDIT:
You could get rid of a little bit of the white space on the right by changing the iframe width from 1000px to 700px like so:
<iframe scrolling="no" frameborder="0" style="width: 700px; height: 650px;" src="http://www.mlsfinder.com/ca_sandicor/raphaelshapiro/index.cfm">
....
</iframe>
EDIT 2:
To make your site wide so that it fits this iframe you will need to do the following (in each case note the width difference) also this assumes that you are getting rid of the background image...
<iframe scrolling="no" frameborder="0" style="width: 850px; height: 650px;" src="http://www.mlsfinder.com/ca_sandicor/raphaelshapiro/index.cfm">
</iframe>
div#main_full {
float:left;
margin:0 0 6px;
width:850px;
}
#content {
margin:0 auto;
overflow:hidden;
padding:10px 0 0;
width:1050px;
}
div#wrapper {
margin:0 auto;
padding:10px 0 0;
width:1050px;
}