The hover attribute only works on the A tag in Internet Explorer, while in other browsers you can apply it to any number of other elements. So unless you can fenagle your code to have a block-level A tag fill your entire TD cell and change ITS background, you're SOL in IE.
[Edit] If you aren't worried about IE, though, the solution lies in putting a DIV tag in your TD cell, and applying the formatting to it. CSS applied to a TD is usually processed as inline, so you're going to need a block-level element in there it you want it to naturally span the entire width of the cell.