Anti-Virus freeware & free-edition

ClamWin Free Antivirus for Windows , open-source freeware.

Clam AntiVirus for UNIX

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Free Edition ( Not Freeware )

Ad-Aware Free Anniversary Edition

Spybot - Search & Destroy 免費下載接受捐款 (use Paypal)

AVAST 有 free版 , not freeware.

AVIRA 小紅傘 有 free版 , not freeware. 會有廣告.