We've not had one for ages. Problem is you end up compulsively viewing forums!!
Yup, I'll agree with that! However, you also end up reading more books, being more sociable, etc etc.
Also, you'll really annoy the TV licensing people, who won't be able to comprehend anybody not having a TV, and will send you red letters implying you're a criminal on a monthly basis

.
Currently, though, if your pc can pick up programmes as they are being shown you will be liable for the licence. (according to TV Licensing site)
Yes, this is correct. However, I believe I-player etc does not count (as not viewing at time of original broadcast). This is academic in our case, since our interweb connection isn't fast enough for I-player anyway!
are you not liable for the non-comercial radio as well on a tv licence?
No, the radio license was abolished in the early 70's IIRC.
Aw, just go for it. Give it a trial for 6 months and see how you go. Chances are, you'll never look back!