static extern bool Process32First([In]IntPtr hSnapshot, ref PROCESSENTRY32 lppe);

    static extern bool Process32Next([In]IntPtr hSnapshot, ref PROCESSENTRY32 lppe);

        PROCESSENTRY32 procEntry = new PROCESSENTRY32();

static extern bool Process32First(IntPtr hSnapshot, ref PROCESSENTRY32 lppe);

static extern bool Process32Next(IntPtr hSnapshot, ref PROCESSENTRY32 lppe);

public struct PROCESSENTRY32

I found a different PROCESSENTRY32 structure I needed to use on Windows Mobile (6.x)