adding cast iron radiator to existing system

i am wondering if it is a good idea to add a radiator to my basement. it's pretty cold down there(50) and i have acquired a beautiful radiator that matches all the radiators in my house. i have a hot water boiler and the system has a feed line and a return line. will this screw up the functioning of the system? would i be able to turn the radiator off at the valve when not in use and not mess up the circulation? and will the hot water circulate properly throughout the whole house when the radiator is opened up? i firmly believe in the "if it ain't broken" school of thought, but heat in the basement would be great. thanks for the help, bela