Not sure what you mean with the "Windows 7" visual style... Many Windows 7 windows and controls still look like regular WinForms controls to me. Although this also depends on your Windows settings.
To get a more modern look and feel you can use
WPF[
^], but if you are not used to that kind of programming it can be a difficult learning curve.
If you want to get the same results in WinForms you could
create your own Controls[
^], but that is no easy task. Many companies have created their own Controls library for different platforms. I am currently using
DevExpress WinForms Controls[
^] at work, which look a lot better than the standard WinForm Controls.