Me uses a china make one named Gadmei. It is quite good one. But no FM
Pros of Ext. TV Tuner Card
1. No need of turning on the Comp.
2. No Drivers, No sofware, No hassles
3. Excellent picture quality compared to the internal one
4. Cheap
Cons
1. You cannot record your favourite programmes
2. Seperate Power required
If recording is no option for u, Go for the external one.
If you gonna buy an internal buy, i recommend not to buy the Mercury. Go for something like Pinnacle PCTV Plus, which is a bit costly, but is a good one.