On Windows 7, with 4 GB of RAM, the 2012 version of BitDefender Total Security 2012 seems to require fewer resources than the last. It does not conflict with other software installed on the PC.
The points that I feel are negative:
1) systematic control of peripherals (USB key)
2) the improbable protection against spam email
If a person knows how to set the antispam, thank you
to report it.