Removing Galvanized from copper fitting??

I am remodeling a half bath right now. today i took off one of the valves to start measuring for bead board. i noticed there was a lot of crud inside the pipe. on closer inspection it is galvanized i believe. i cut open the wall to find copper pipe with a copper tee. and then a piece of pipe threaded to it. the house was built in '59. so the pipe could be original. it didn't want to budge with my channel locks. any tips on taking something like this out?? i want to replace it with a copper piece.
thanks for any help..

 

If this is an old piece of galvanized pipe screwed directly into a copper fitting, it is probably completely ocrroded together by electrolysis by now.
You can spray the connection with WD-40 and let it soak a while, and then try to unscrew the galvanized nipple counter-clockwise with a pipe wrench.
Hold the copper fitting with the channel-locks or another pipe wrench as backup in the opposite direction.
If it won't come out or the threads are ruined, you're going to to have to solder in new copper pipe and fittings, and then you can use a 1/2"-to-3/8" compression-type shut-off valve on the copper pipe from the wall.
Good Luck!
Mike