[64-bit] Install AVG free and pro anti-virus for Ubuntu 64-bit

[Artificial Intelligence]

Guide updated - Now also containing the free version.

[pedro_cesar]

When I try to run:

sudo dpkg -i free-avg.deb

I receive this error message:

pedro@pedro-desktop:~/Setups$ sudo dpkg -i free-avg.deb
(Leyendo la base de datos ...  
122312 ficheros y directorios instalados actualmente.)
Desempaquetando avg75fld (de free-avg.deb) ...
dpkg: error al procesar free-avg.deb (--install):
 intentando sobreescribir `/opt/grisoft/lib/libgcc_s.so.1', que está también en el paquete avg75lms
dpkg-deb: el subproceso paste fue terminado por la señal (Tubería rota)
Se encontraron errores al procesar:
 free-avg.deb

This is the translation (which might not be 100% acurate)

pedro@pedro-desktop:~/Setups$ sudo dpkg -i free-avg.deb
(Reading Data Base ...  
122312 Files and directories currently installed.)
Unpacking avg75fld (from free-avg.deb) ...
dpkg: error while processing free-avg.deb (--install):
 trying to overwrite `/opt/grisoft/lib/libgcc_s.so.1', which is also currently in the package avg75lms
dpkg-deb: the subprocess "paste" was terminated by signal (Broken Pipe)
Errors were found while processing:
 free-avg.deb

P.S.------------------------------------------------------------------------------------------------
I am dual booting with Windows Vista, and already have FireStarter installed, I wanted to know how strong is the AVG FREE edition's protection? Do I need to/should configure some other things to make my system more secure? Which things? Is it enough with what I already have (assuming I do install AVG AntiVirus)?