Thank You, Tag Fairy! Well done!
For those of you still having trouble cutting and pasting. I wasn't able to do this, either. This is what I did to solve the problem.
1. Right click on the image.
2. Click on "properties".
3. Copy down "address".
4. Go into you "User CP".
5. Click "Edit Signature".
6. Click on this small button that looks like a small postcard with mountains on it.
7. Manually enter the address of the image.
8. Click "OK".
This worked for me. Hope it helps. Good luck!!!