You can download the trial version from www.symantec.com and evaluate it. However Nortan is not giving any free version of its software. Some torrents are available but using them is illegal and you will be procecuted if found guilty. Also such illegal downloads may contain trojan programs that will cause harm to your computer and your personal information.
What I suggest is:
Purchase the antivirus software from your local dealer where you can get good discount.
Choose an alternative security software. For example, Kaspersky Internet Security software is available at Rs.350 in India at local dealers compare to Rs.700 on website. Check out your local dealer. I found Kaspersky better than Nortan and it runs faster as well, takes less memory.
http://www.google.co.in/url?sa=t&source=web&cd=1&ved=0CB0QFjAA&url=http%3A%2F%2Fwww.symantec.com%2F&ei=dYlvTIb0CpCiuQPogrGZBQ&usg=AFQjCNHEtxH-1Kz6ZexubOuKM5QmQB3lJw&sig2=7g-mAZzBRQzwXLesb85RdA