[jQuery] Drag is very smooth on Firefox, but it is total screw on IE7!

[jQuery] Drag is very smooth on Firefox, but it is total screw on IE7!

I'm using jQuery UI for drag and drop and Mootol for sortable, b/c we don't use drag+drop_sort on the same element!
It works very well in FF! The darging is very smooth!
But in IE, it is very screw! It seems IE can parse/draw enough fast! When i dragging a item, it happens slowly.
Look at this on IE7<br clear="all"><a href="http://www.trademerchants.com/delnow/kurei/ae/index_template.php">http://www.trademerchants.com/delnow/kurei/ae/index_template.php</a>
And you will see my issue!
Does anyone how to solve this?
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/*****************************************
@name Quoc Vinh Nguyen
@email Kurei@UrbanJar.Info
@alias Vincent Nguyen
@site Axcoto.Info
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