If the Mediacom site is correct, you will have more clear QAM than anyone I have heard of. Most of the channels will be SD, with just the local broadcast in HD (see the HD lineup at the bottom of the list). You should be able to receive all of these with a QAM tuner card. I have no personal experience with the 1600, but the sentiment on this forum is that there are now better choices from Hauppauge, such as the 1150 for PCI or 1250 for PCIe. Depends on whether your motherboard has a PCIe slot.
And, they tell you the QAM channel. Amazing. Charter doesn't even admit that they exist.
HTPC: E7500, Saphire HD5450, Firewire Network Recorder/Avermedia Duet A188, NPVR 3.3.8, Win7 Pro
Test: Asrock 890GM Pro 3, Athlon X2 255 , internal HD4290, ATI Theater 650Pro, NPVR 3.3.8, Win7 Home Premium
Backup: Athlon 3200, Nvidia 7600GT, Network Recorder, NPVR 2.5.5, Win7 Home Premium