Index: wp-admin/js/plugin-install.dev.js
===================================================================
--- wp-admin/js/plugin-install.dev.js	(revision 16884)
+++ wp-admin/js/plugin-install.dev.js	(working copy)
@@ -1,14 +1,18 @@
 /* Plugin Browser Thickbox related JS*/
+var tb_position;
 jQuery(document).ready(function($) {
-	var thickDims = function() {
-		var tbWindow = $('#TB_window'), width = $(window).width(), H = $(window).height(), W = ( 720 < width ) ? 720 : width;
+	tb_position = function() {
+		var tbWindow = $('#TB_window'), width = $(window).width(), H = $(window).height(), W = ( 720 < width ) ? 720 : width, adminbar_height = 0;
 
+		if ( $('body.admin-bar').length )
+			adminbar_height = 28;
+
 		if ( tbWindow.size() ) {
-			tbWindow.width( W - 50 ).height( H - 45 );
-			$('#TB_iframeContent').width( W - 50 ).height( H - 75 );
+			tbWindow.width( W - 50 ).height( H - 45 - adminbar_height );
+			$('#TB_iframeContent').width( W - 50 ).height( H - 75 - adminbar_height );
 			tbWindow.css({'margin-left': '-' + parseInt((( W - 50 ) / 2),10) + 'px'});
-			if ( ! ( $.browser.msie && $.browser.version.substr(0,1) < 7 ) )
-				tbWindow.css({'top':'20px','margin-top':'0'});
+			if ( typeof document.body.style.maxWidth != 'undefined' )
+				tbWindow.css({'top': 20 + adminbar_height + 'px','margin-top':'0'});
 		};
 
 		return $('#dashboard_plugins a.thickbox, .plugins a.thickbox').each( function() {
@@ -17,11 +21,13 @@
 				return;
 			href = href.replace(/&width=[0-9]+/g, '');
 			href = href.replace(/&height=[0-9]+/g, '');
-			$(this).attr( 'href', href + '&width=' + ( W - 80 ) + '&height=' + ( H - 85 ) );
+			$(this).attr( 'href', href + '&width=' + ( W - 80 ) + '&height=' + ( H - 85 - adminbar_height ) );
 		});
 	};
 
-	thickDims().click( function() {
+	$(window).resize(function(){ tb_position(); });
+
+	 $('#dashboard_plugins a.thickbox, .plugins a.thickbox').click( function() {
 		tb_click.call(this);
 
 		$('#TB_title').css({'background-color':'#222','color':'#cfcfcf'});
Index: wp-admin/network/index.php
===================================================================
--- wp-admin/network/index.php	(revision 16884)
+++ wp-admin/network/index.php	(working copy)
@@ -35,7 +35,9 @@
 wp_dashboard_setup();
 
 wp_enqueue_script( 'dashboard' );
+wp_enqueue_script( 'plugin-install' );
 wp_admin_css( 'dashboard' );
+wp_admin_css( 'plugin-install' );
 add_thickbox();
 
 add_screen_option('layout_columns', array('max' => 4, 'default' => 2) );