I have never used the Photoshop -> HTML method. I personally prefer slicing the items as needed and them arranging them using XHTML & CSS.
Now, I have checked your site. I haven't checked the code yet but I would mention about the image problem in IE. IE sometimes leaves a 3px margin below each image. But, right now the problem is more becoz of direct conversion from PS -> HTML. Maybe you are right in saying that you have too many slices but if it looks good ni Firefox then there has to be a cross browser issue. I don't have access to Firefox right now. Will check out in a while.
Btw, any update on this?
In case you have hands on exposure with HTML then you can check out
this tutorial about CSS based layout.