What's the model number of your TV?
If you haven't bought the Promedias yet, you might want to think about something else. As Slick5150 mentioned, volume control might get a little messy. If your TV has RCA analog audio output (or 3.5mm I suppose), it may also have variable output which would mean you could control the volume with the remote. You'd still have volume control on the speaker system though too.
If you have future upgrade plans for your audio system, you'll probably have to start from scratch again. That isn't the end of the world since the Promedias will probably hold their value well, but if you want to take the first steps toward a system you can upgrade over time, the Promedias are a dead end.