This looks not unlike a windows application.

The menu is just a small part of it, but if you realy want it to look like a windows 98 application, it helps a lot :o).

Most of the effect are done in the HTML, using inline style.
Maybe fidling more with the CSS file can improve it further.

Note that it takes the colors from your own desktop settings. (You will only se this, if you are not using default colors on your desktop)
This is done by using some special CSS color deffinitions.
No graphics used.