for the last line: yes, i'm using windows xp, but the floppy of this mouse's software was fallen into water;) so i was cant install the software. with win's driver, the 4&5th buttons are really for back & forward in IE.
(now i downloaded the software)
so, yeah, it is optical, it haves 5 buttons, 2 scrolls. (for horizontal and vertical scrolling). this mouse rulz!