Hi Adam,
Avast has three products
1. Avast! Free
2. Avast! Pro
3. Avast! Internet Security.
Firewall is avaliable in the third and full version that is Avast! Internet Security. It will cost you $49.99 for 1 year for 1 computer.
The following system requirements are recommended in order to install and run avast! Internet Security 6.x on your computer:
Microsoft Windows XP Service Pack 2 or higher (any Edition, 32-bit or 64-bit), Microsoft Windows Vista (any Edition, 32-bit or 64-bit) or Microsoft Windows 7 (any Edition, 32-bit or 64-bit).
Windows fully compatible PC with Intel Pentium III processor or above (depends on the requirements of used operating system version and other 3rd party software installed).
256 MB RAM or above (depends on the requirements of used operating system version and other 3rd party software installed).
370 MB free space on the hard disk (to download and install).
Internet connection (to download and register the product, for automatic updates of the program and antivirus database).
Optimally standard screen resolution not less than 1024 x 768 pixels.
Hope you are happy with us today. Have a wonderful day.. Good Karma!