CSS property text-shadow
is not supported by either browser (IE8, IE9) and box-shadow
is only supported by IE9
You best solution is just not to have the glow effect in those early browsers and give users of those browsers a warning that the site looks better in a modern updated browser.
To achieve what you want in those browsers you would have to create transparent png
images and swap them out on :hover
. But this because real messy (especially when you have to keep adding new text or change text) and is not efficient.
Do not create more work for yourself with something that just applies to aesthetics.