Avast! 4 Professional Edition is a collection of award winning, high-end technologies that work in perfect synergy, having one common goal: to protect your system and valuable data against computer viruses. It represents a best-in-class solution for any Windows-based workstation. This page demonstrates its most important features and provides links to further resources.
The program itself requires about 20MB of hard disk space; the remainder of the recommended space is reserved for the virus recovery database file and its index.
The upcoming antivirus which is surprisingly low on resources and pretty effective and fast in scanning.