hover: replace image Options

[aspartame_i]

I found this code to replace images upon hover

http://www.createblog.com/forums/index.php?showtopic=15520

which states that

<!-- begin code provided by createblog.com --><br /><br /><!-- begin code provided by createblog.com --><br /><a onmouseover="document['fpAnimswapImgFP1'].imgRolln=document['fpAnimswapImgFP1'].src;document['fpAnimswapImgFP1'].src=document['fpAnimswapImgFP1'].lowsrc;" onmouseout="document['fpAnimswapImgFP1'].src=document['fpAnimswapImgFP1'].imgRolln" href="javascript:void(0)"><br /><img border="0" src="URL OF IMAGE HERE" id="fpAnimswapImgFP1" name="fpAnimswapImgFP1" dynamicanimation="fpAnimswapImgFP1" lowsrc="<br />SECOND URL HERE" width="PIXELS OF IMAGE" height="PIXELS OF IMAGE"></a></p><br /><!-- end code provided by createblog.com --><br /><br /><!-- end code provided by createblog.com -->

Unfortunately, I found this code to be useless; although, admittedly, possibly due to my error. I'm not sure what the pixel values indicated represent. Is it the size of the original image, the original size of the replacing image, etc. Does anyone know how I can make this code work, or if there is another one which I can use?