Here's the text I'd put there - a slight modification of RejZor's one:
avast! antivirus is based on the comprehensive ALWIL Software scanning technology available since 1988. Featuring fast incremental updates and advanced multi-layer real-time protection of all infection vectors, it provides high security against virtually all kinds of malware. avast! is offered in multiple editions, starting with the FREE Home Edition for personal use, Professional Edition with extra features, PDA Edition up to the Network Edition with centralized administration for large corporate networks running Windows, Exchange and ISA servers. In addition, ALWIL offers free 24/7 support on their online forums and via support telephone/e-mail.
Vlk, that is very professional...
but I do have one question (don't I always?!)
Can you not at least capitalize the A in avast! I know it's not usually capitalized, but in writing it in this text form, it would look better...jmo, of course! It also would balance out the capitalization of ALWIL, FREE, and the other first letter capitalizations.
New readers may think it is a proof reading error...
I'm sorry that I am so "picky!"

I just want readers to be impressed and come to avast! and stay and buy

cojo