swanny2 you probably can still use it, you install it and run it for a year and after that you have to pay for the updates, it about £20 a year BUT because its so old if you do get into trouble Norton will not help as they no longer support it as I discovered at the beginning of the year. Basically a virus got in mucked up the anti virus, I asked Norton for help and they said the money I paid was for being able to download the updates but they would not help as they no longer supported it. Because of this I moved to AVG, its free and has daily updates instead of Nortons weekly ones. Up to you but I think you'd be better off with one of the free ones.
Anti virus updates come in two flavours, new virus signatures to enable the program to identify new nasties and where necessary program updates to enable the program to deal with the new threat. Simply installing virus signatures to an unsupported old variant anti virus will enable it to detect, but not necessarily do anything about a new threat, as unsupported versions don't get the necessary development work to update them. So IMHO installing any unsupported AV isn't a good idea, as it can't clear all current threats. Either use one of the free packages suggested or if you really must cough up for a commercial license, get an OEM package click here