I've had another quick look and the above mentioned problem is also attributable to your 2 flash anims. Simply taking out the 2 graphics I listed will not fix it as easily as I first thought.
images/logo.swf -> width specified; 151
top_aboutus3.swf -> width specified; 645
Total width = 796
ie 24 pixels too wide for 800x600
Total width of images on page currently = 823 pixels (taking either r2 or r3)
images/main_r3_c16.gif both = 27pixels
takes overall width without, down to 796 which is still too wide (this is the effective width of your 2 swf's. You need to put your banner back into fireworks/dw and try and skim another 26 pixels off it.