The issue is your line-height: 0px; setting on the td - which really doesn't make sense.
You should remove this.
You will then see everything will space out too much and you need to then correct the other issues.
For instance in li.head you can remove the padding-top and just give the cell a height:23px;
That will fix up the top row.
Now get rid of all the extra <br> tags in the <ul id="Nav2"> section and you will see it improve.
There will still be some more formatting issues but hopefully this will keep you going in the right direction.
Let me know if you need more help.