Hi Alex.

You should read all the replies in this thread before posting. :)

The following is the 3rd reply:-

Tyrion wrote on Dec 19^th, 2009 at 11:57pm:

Try reinstalling your 757. If there are no model.RRW or model.PWW folders in the CS_B757-200 folder, you can't install winglets, as this are the models that have the winglets. As soon as you have the folders (and the correct files in them) ACE will do the job just fine!

Ace works fine for me. But I also found that by changing the lines as per my first reply:
In the aircraft.cfg look for ui_wglts=0 and change it to ui_wglts=1.
Don't forget to backup any files you are going to modify just in case you make a mistake that might ruin it.  ;)

Mark