For what it's worth, I just inserted the enclosed if statement in my code, and it works nicely, jagged edges and all
self.logo = images.getLogoImage()
if wx.GetOsVersion() <= (18, 5, 0): #win2k
self.logo.SetMaskColour(0xf0,0xf0,0xf0)
self.logo.ConvertAlphaToMask()
bmp = self.logo.ConvertToBitmap()