if all the images will be the same width (as the two currently are) then give the ul that width and center it with auto left and right margins

the images are 1122px wide - why would you give the parent ul a width of 500px (furthermore, why would you do it via inline styling)? I said to use left and right auto margins (like your nav uses) - not the align attribute (which is deprecated - use css).

  .rslides { 
    width: 1122px;
    margin: 0 auto;
  }