Which desktop are you using?
KDE is fairly Windows-like by default, and I set up my XFCE installs to look largely the same. I personally like to have the window buttons look fairly Windows-like, easily done in both KDE and XFCE. Put the task bar on the bottom, use a single task bar, and the basic layout is the same. I suppose you could even change the application launcher menu to look like a START button.
Depending on the desktop you are using then you should be able to find a theme that is visually pretty close.