What you should try is the getElementById. I would suggest this approach:

document.getElementById("table").style.width=maxWidth

OR you could also try this (if the above doesn't work)

document.getElementById("table").setAttribute("width",maxWidth)

Please note that this method is not supported by all browsers. I think 
it's supported in IE and Netscape 7.0+, but I am not sure.

If you don't have to do this on the fly, you can do this:

document.write('<table width="' + maxWidth + '">blah</table>')