Layer positions

I've got a layer at 343 pixels from the left at 1024 x 768 and when the user has a different resolution the layer is at the wrong place. It has to be exactly at that place. I tried to set it at 33.5 % which moves the layer a bit, but not exactly enough. Is there a way or do i have to redesign the page ?

The reason for why the layer has to be exactly at that place is that my page uses a big centered table and the layer is on it. The layer contains an iframe. I could ofcourse merge the needed cells of the table, but then when i view the page the table becomes much higher. Every cell becomes about 33 % higher than written.

I'm using Dreamweaver 3.

Thanx.