As always, I'd like to advocate the "progressive enhancement" approach, just because I'm anal retentive.
Don't accept this answer, as it doesn't directly answer your question.
Features that don't add functionality to a website should be carefully weighted: a color fade on the links isn't that vital, I think. So why should everyone visiting your site download jQuery + jQuery UI only for that "feature"?
Add transitions only to those who support transitions. It's also easier for you to maintain this code. It's also hardware accelerated on mobile devices.
.menu li a {
color: #000000;
-webkit-transition: color 1s linear;
-moz-transition: color 1s linear;
-ms-transition: color 1s linear;
transition: color 1s linear;
}
.menu li a:hover {
color: #FFFFFFF;
}
Maybe the people that use obsolete browsers (IE <= 9) will get it, that they need to update or change, if not every single site is developed "for them" and at the cost of all others.