with Direct Draw 7 - Do you need to lock the destination surface befor performing a blitting routine? Because when I do a blit with DD6 it works switch the surfaces to DD7 surfaces I get an access violation. Whats up with that?

Nope, you shouldn''t lock it for blitting, the blitting functions do it for you, you should only lock if you are planning on manipulating the pixels directly, this was true in DD6 too, so if you dont lock before a blitting you will be safe in both versions.