Steve,
Your question is too generic, so to say. If you could explain in more detail
what exactly look and feel you want to give to your application, we might be
of much greater help.
Some of the most obvious options are:
a) Windows XP style
b) Skinned interface (WinAmp, Windows Media Player etc.)
c) "Flat" style (Visual Studio .NET)
P.S. Such questions best match the
microsoft.public.dotnet.framework.windowsforms newsgroup.