Highlighted menu

Okay, i am trying to create a menu so that when your on for example the “About Us” page the menu image stays on the rollover state to show the guest which page they are on.

My menu is built in css.

I haev the code:

<li <?php
if (is_single('5'))
 {
echo " class=\"photos2\"";
}
?> >

which does work. But how can i give it an else statement that will by default give it a different css class?

I tried:

<li <?php
if (is_single('5'))
{
echo " class=\"photos2\"";
}
else
{
echo " class="\photos\"";
}
?> >

But this would not work…any help???

Thanks!