var optionsstring = "dialogHeight:340px; dialogWidth:240px; resizeable:no; scroll:no; status:no; center:yes";
window.showModalDialog(document.forms[0].dbURL.value + "/OOOP?OpenForm", "", optionsstring )

//dialogHeight: sHeight 
//dialogLeft: sXpos 
//dialogTop: sYpos 
//dialogWidth: sWidth 
//center: ( yes | no | 1 | 0 | on | off ) 
//dialogHide: ( yes | no | 1 | 0 | on | off ) 
//edge: ( sunken | raised ) 
//help: ( yes | no | 1 | 0 | on | off ) 
//resizable: ( yes | no | 1 | 0 | on | off ) 
//scroll: ( yes | no | 1 | 0 | on | off ) 
//status: ( yes | no | 1 | 0 | on | off ) 
//unadorned: ( yes | no | 1 | 0 | on | off )