Dr. Web Antivirus
ESET Smart Security
MS Live OneCare
ZoneAlarm Security Suite
The three core applications are the antivirus engine, the mail-scanning engine, and a task scheduler. Many common program options are available by right-clicking the tray icons, so you don't need to drill down through the program's configuration menus as much as you might for some other apps of this kind. Each program's defaults seem to be decent for everyday use: by default, Dr.Web's protection traps pretty much all file creation and access actions, including anything downloaded from the Web.
The program's creators claim they employ an intelligent scanning engine that doesn't need to constantly rescan the same files. Malware, adware, and hacking tools are all broken out into their own categories, so each can be handled differently from the other if you're inclined to do so. Each type of threat can be given a default action and a "what to do if this fails" action -- for instance, a virus could be defaulted to "move to quarantine," with "block" as the fallback action in case the virus can't be moved. I've long been in favor of regarding malware/adware as viruses, but it's nice to have this added degree of flexibility in case for some reason you need to have a given piece of adware running.
Doctor Web Ltd.
$40 for 1 PC/year
There are some other things about the program, aside from its relatively limited scope of protection, that also are irritating. For one, the program populates the system tray with three icons: one for the e-mail subsystem, one for the antivirus system itself, and one for the program's task scheduler. It's not clear why they use their own scheduler instead of Windows's native scheduler. Also, the anti-spam system is even less configurable than TrustPort's anti-spam system -- for one, there's no visible way to even control the sensitivity of the spam filter. It's possible to change how it stamps messages suspected of being spam, though: by default the message subject is prefixed with "[SPAM]," but you can change that as needed. What's unforgivably primitive is the whitelist/blacklist function, which is nothing but a pair of text boxes. Being able to point to an e-mail client's address book or having some other mechanism that's a little more flexible would help.
In sum, Dr.Web is limited in scope, if efficient in its protection. If you eventually decide you need broader coverage, though, you will probably have to go to an entirely different application, unless Dr.Web is significantly expanded in future revisions.