a 62% jpg or 128-colour png8 would both be less than a third of the size
Also, your nav bar can't decide whether it's upper case or not - if you like upper case, stick a text-transform:uppercase in there to avoid problems with fingerfarts
Put some margin on the left hand side to make the text/menus a little more comfortable to read. 2 or 3 pix should do it (more if you want, but you need something)
It's not me you have to worry about, it's your visitors. What will they think when they get presented with a strange pop-up box that harps on about accepting something that's untrusted?
Will your target audience understand what that means?