The way I do it involves a bit more manual effort:
Step 1: Get the best selection around what I want with the tools available. Generally it's the lasso tool set to "smart edge", but it varies.
Step 2: Create a new layer, and use the paint bucket to flood-fill my selection on it with a colour not used in the picture - shocking pink or bright green for example.
Step 3: Dismiss the selection, and set the opacity of the new layer to 50% or so (you need to be able to see both the solid colour fill and the picture underneath)
Step 4: (The tedious bit) Zoom in on the picture and use the brush and eraser tools to fine-tune the selection. When you've finished, you'll have a solid colour area sitting exactly over what you want to cut out.
Step 5: Use the magic wand to select the solid colour block
Step 6: Switch layers to the one with the picture in it
Step 7: Feather the selection, if you need to
Step 8: Cut & paste the selection to wherever you need it.
-- Chris Hunt
Webmaster & Tragedian
Extra Connections Ltd