I want to hide my IP, so that I could not be tracked. Please suggest a free software for that.
I would recommend the same as Charlie: Tor is the best solution. But you can see other alternatives to Tor and what people think about them here: http://alternativeto.net/software/tor/
UltraSurf http://ultrareach.net/ free
Invisible Browsing http://www.amplusnet.com/invisiblebrowsing/invisible-browsing.htm shareware
use free vpn service offered by vpntool.com. its very easy to connect and you don't need to install nay software unlike tor as mentioned above.
Where on the site do you really see that the VPN Tool is "free" - with a 14-day money back guarantee? Huh? Bogus.
It says it's free for Windows XP in bold red letters. But it also explains which credit cards are accepted and the money back guarantee you mentioned. To sign up you are not asked credit card details, though. The WOT rating is ok.Whatever you do, do not share your credit card details!
TOR - http://www.torproject.org