When I opened up the picture in PS, it was already set to grayscale. Sorry, I'm not familiar with picture it, so I'm no help there.
To be honest, I always shoot color, then convert. Shooting color does two things. One, sometimes images just look better in color, even though you didn't think they would. You can't go back to color, but you can always convert from color to b/w.
Two, I find that by doing my basic edits in color, then converting to b/w, I get deeper tones. It also helps when you want to apply a colored filter. For example, if you shoot in b/w with a red filter (digital cameras can simulate this) it will give you a very dark and dramatic sky. But once you convert to grayscale, you loose the embeded color information.
As soon as your comfortable with your cameras controls, start shooting in RAW. You'll be amazed how versatile it is. You can download Pixmantec's Rawshooter for free. It fully supports the XT.