first off.. the little antenna is the UHF antenna for TV2 remote. Based on how you are describing things I don't think you are in single mode yet. Did you press the mode button on the Receiver to get you into single mode? Just having TV2 off does not put you in single mode. Couple of questions to ask your self.
1) Am I either watching TV in the living room or the bedroom or will there be cases where I watch in both. IF 99% of the time it is a either one or the other then keep your 722 in single mode.
2) In single mode you should be able to watch something while recording something else no problems. If this is not the case, You are most likely in Dual Mode and I would suggest reading the manual and the tips section on the top of the 722 support forum. Also there is a card that describes record plus. If you are going to run your DVR in dual mode I highly suggest reading the help card so you understand how things work in dual mode.
1) Am I either watching TV in the living room or the bedroom or will there be cases where I watch in both. IF 99% of the time it is a either one or the other then keep your 722 in single mode.
2) In single mode you should be able to watch something while recording something else no problems. If this is not the case, You are most likely in Dual Mode and I would suggest reading the manual and the tips section on the top of the 722 support forum. Also there is a card that describes record plus. If you are going to run your DVR in dual mode I highly suggest reading the help card so you understand how things work in dual mode.