If Windows Messaging is working OK, you CAN safely delete the old
MSExchange folder. But since you're concerned about things having slowed
down, you might want first to simply drag the folder into the Recycle Bin
and leave it there for a while to see if you're satisfied with things
before you delete it for good.
NOTE: Delete ONLY the MSExchange folder that's located in the Program
Files directory. Do NOT delete the folder labeled simply "Exchange" that's
located directly on your C drive -- the files there are still needed by