"But an AVG scan finds nachi.b. How did that happen?"
The short answer is no antivirus will stop WORMS like MS Blaster and its varients. The "How"? is simple. The machine was connected to the internet without SP1 or using XP' own firewall.
Here's an article on MS Blaster and varients -> http://www.microsoft.com/security/incident/blast.asp
This is a little confusing so bear with me. My brother bought an E-machine with XP Home SP1 pre-installed. No Windows Updates show in Add/Remove.
He goes to Windows Update and writes down the numbers of the one it lists, so I can download on my faster connection and burn to disk for him.
Update does not list that he needs 824146 or 815021. But an AVG scan finds nachi.b. How did that happen?
A lot of the updates it lists, have never been offered to me with XP Pro and are not on my computer. When I go to each KB article, it offers downloads for XP and XP embedded. I don't know which ones to get. What exactly does XP embedded SP1 mean? Would it be possible that is what is on his machine, and how can I tell for sure? The more I Google, the more confused I get.

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