Battery or Alternator?

I have a 2000 Chevy Monte SS and I'm having issues with either the battery or the alternator or the battery cables. When it first started having problems, I would try to start it and it would just click like the battery was dead, I could jiggle the battery cables and it would start up. Then it wouldn't even do that and I started having to get a jump if I didn't drive it every day (like on the weekends) if it sat for more than a day I would need to jump it. I assumed it was the battery and changed it last night. This morning on my way to work the battery dummy light came on, it never did that before, and my radio kept shutting off and coming back on (it is hard wired to the head light fuse, that's how I bought it). The person who had the car before me had a modified sound system and there are cables still attached to the alternator but the other end is taped with electrical tape. So I go to Advanced Auto to have my alternator tested and this is what it said: RESULTS Charge Required, Voltage: 12.15V Measured: 347 CCA, Rated: 650 CCA, Temperature: 95F, BATTERY CHARGE IS LOW AND MUST BE CHARGED TO DETERMINE CONDITION: Starter Test:  RESULTS: Cranking Normal, Voltage: 11.02V, Amps: 0.0A, Time: 3.51S. Charging System Test: RESULTS: LOW VOLTAGE No Load: 11.88V, Loaded: 11.50V, Max, Min, NO LOAD LOADED, .024V Ripple 46mV, -.024V. Charging system problem, check belts, connections and grounds alternator service recommended if connections are good.

So I'm wondering if I need to take those extra cables off that were left from the sound system or if it really is the alternator. It doesn't drain slowly and die or anything and when the radio shut off and came back on it didn't slowly shut off either.

PLEASE HELP!!
Brandy