I asked on the AntiVir anti-virus forum, and they stated that they no longer support Win 98/ME. I think that they dropped support in mid-2007.
AVG has released a new v8.0 of it's commercial anti-virus and it no longer supports Win 98/ME. The AVG Free Edition v7.5 is still available, and if AVG follows their past pattern, a Free Edition of v8.0 will follow in a few to several months. AVG has explicitly stated that: "* Some older operating systems such as Microsoft Windows ME, Microsoft Windows NT and Microsoft Windows 98 will only be supported until August 2008 as a minimum."
Avast! has just released v4.8 of their anti-virus, including the free home edition. v4.8 still supports "more Windows versions (from Windows 95 to Vista 64 Bit) than any other anti-malware product."
. In their forum, they stated that the new v5.0 that is under development will continue to support Win 98/ME, although not all features will be supported on Win 98/ME (but that is the case, currently).
So it looks like Avast! Home will be the only remaining full-featured freeware anti-virus package to support Win 98/ME. Fortunately, it has gotten some very favorable reviews.
CNet Download.com rated the new Avast! Home v4.8 as 5 out of 5 stars.
And PC Mag has an on-line review of the new v4.8 of Avast! Home edition, rating it as 4 out of 5 stars - or "very good."
For a commercial product, BitDefender new v2008 requires Win2K, XP, or Vista. But they are still offering their previous version, v10, which supports Win 98/ME. See: http://www.bitdefender.com/site/view/Produ...in98-Me-NT.html
And the BitDefender Free Edition is still available and supports Win 98/ME, but it lacks an on-access, real-time scanner and is an on-demand scanner product only.
Finally, I wanted to mention that the Outpost Firewall Free edition supports Win 98/ME.