If it helps, here's what Dreamweaver says about which errors will occur with which browsers:
Error The onmouseout attribute of the FONT tag is not supported.
Mozilla 1.0, Netscape Navigator 6.0, Netscape Navigator 7.0, Opera 2.1, Opera 3.0, Opera 3.5, Opera 4.0, Opera 5.0, Opera 6.0, Opera 7.0, Safari 1.0
<FONT onmouseover="this.style.color='red';" onmouseout="this.style.color='Blue';" color=blue size=6>
Error The onmouseover attribute of the FONT tag is not supported.
Mozilla 1.0, Netscape Navigator 6.0, Netscape Navigator 7.0, Opera 2.1, Opera 3.0, Opera 3.5, Opera 4.0, Opera 5.0, Opera 6.0, Opera 7.0, Safari 1.0
<FONT onmouseover="this.style.color='red';" onmouseout="this.style.color='Blue';" color=blue size=6>
Warning The Meta tag is not supported.
Opera 2.1
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
Error The SPAN tag is not supported.
Opera 2.1, Opera 3.0
<SPAN style="FILTER: shadow(color=black,strength=6,direction=225); HEIGHT: 1px">
Error CSS property FILTER is not supported
Microsoft IE for Macintosh 5.2, Netscape Navigator 6.0, Netscape Navigator 7.0, Opera 3.5, Opera 4.0, Opera 5.0, Opera 6.0, Opera 7.0, Safari 1.0
<SPAN style="FILTER: shadow(color=black,strength=6,direction=225); HEIGHT: 1px">
Error Value 'shadow(color=black,strength=6,direction=225)' is not supported for CSS property FILTER
Microsoft Internet Explorer 5.0, Microsoft Internet Explorer 5.5, Microsoft Internet Explorer 6.0
<SPAN style="FILTER: shadow(color=black,strength=6,direction=225); HEIGHT: 1px">