I'm going to attempt to write a small tutorial on using the pen tool to cut out selections. When the lasso fails, give this a try. Hope this helps!

1. Select the Pen tool. (Shortcut: P)
http://genji.image.pbase.com/u43/sinushi/upload/27926082.01pen.jpg

2. For this procedure, make sure these options are selected:
http://genji.image.pbase.com/u43/sinushi/upload/27926083.02pen.jpg

3. Zoom in on your image. As much as you want. Now begin placing anchor points around your subject. Don't worry about the curves yet. How many points you pick is up to you. If there's a real tricky part, make a lot of anchor points.
http://genji.image.pbase.com/u43/sinushi/large/27926084.03pen.jpg

4. Change to the "Convert Point Tool"
http://genji.image.pbase.com/u43/sinushi/upload/27926085.04pen.jpg

5. Now click on one of the ponts and drag it to the left or right--which ever way goes with the curve of your photo. For this example, I moved to the left.
http://genji.image.pbase.com/u43/sinushi/upload/27926080.05pen.jpg

6. Do this to the whole thing.
http://image.pbase.com/u43/sinushi/large/27926081.06pen.jpg

7. When you've closed the path and it's bent the way you want, you can right click, go to "Make Selection." Then "Select Inverse" (Shift + Ctrl + I) and delete the backround.

This is only the beginning to what you can do with this amazing tool. Essentially it makes a vector-based path and you can save that shape and then using the "custom shape" tool, make it any size you want with no pixelization.

Questions? Don't understand a step? Let me know!

~Chris
--
www.pbase.com/sinushi
http://image.pbase.com/u36/sinushi/medium/23440544.Sinushi.jpg