In ./moodle/install.php, the following construction:

<a href=javascript: void(0)><img src=./pix/help.gif height=17 width=22 alt=Helpborder=0 align=middle title=Help onClick=return window.open('install.php?help=memorylimithelp', 'Help', 'menubar=0,location=0,scrollbars,resizable,width=500,height=400')></a>

is a 'link' to a page that is completely inaccessible for people using non-javascript-enabled browsers. I think the only thing that using javascript here really gains you is the opportunity to break the toolbars and such in the spawned window. Couldn't the link be included in the anchor element as well?

<a href=install.php?help=memorylimithelp title=New window: Help for memory limit caution.><img src=./pix/help.gif height=17 width=22 alt=Helpborder=0 align=middle title=Help onClick=return window.open('install.php?help=memorylimithelp', 'Help', 'menubar=0,location=0,scrollbars,resizable,width=500,height=400')></a>

Also, there's no space between the end of the alt attribute and the border attribute. border is deprecated in html4.0, and may be disallowed in XHTML1... not sure about that part. I'd suggest removing the 'border' attribute from the img tag, and replacing it with style=border: 0px;.