From someone who knows nothing about IT and all it's wonders.

Is it possible to link your PC to your flat screen TV (plasma) and is it worth it in the areas of picture and sound quality ?

Yes, for best picture and sound quality use HMDi cable.

My plasma 5+ year old Panasonic 42" has 2 HDMi ports, and have one on my Graphics card

with this option also watch TV in full HD.

Yes, for best picture and sound quality use HMDi cable.

My plasma 5+ year old Panasonic 42" has 2 HDMi ports, and have one on my Graphics card

with this option also watch TV in full HD.

Thanks,

I'll let you know how I get on with the set up

Even if your pc does not have hdmi you can connect via a VGA cable.

If you take this path you will need a second cable for sound.

I am not sure that TV speakers have much to offer over the pc, marginal at best.

If you want good sound then go for a separate amp and speakers to match