ajustar tamaño??

[Gurrutello]

El script seria algo asi
<script>var width = screen.width;var res =(((!(640-width))*1)+((!(800-width))*2)+((!(1024-width))*3)+((!(1152-width))*4)+((!(1280-width))*5)+((!(1600-width))*6)); if(!(res)) res = 1;if (res=='1') {window.location='http://www.640x480.com'}if (res=='2') {window.location='http://www.800x600.com'}if (res=='3') {window.location='http://www.1024x768.com'}if (res!='1' && res!='2' && res!='3') {window.location='http://www.otra.com'}</script>

modifica las urls con las que tu quieras.