In photoshop, if you go to the image size dialogue, what does it say the resolution is under pixel size? Anything more than 72 pixels/in is unnecessary for the web, so lower it to 72. Actually, before you do that, make a note of the width and height at the top under 'pixel dimensions' because you'll probably have to reset it.
If you want, PM me and I'll see if I can get it down to a manageable size for you.