The issue here would be what to understand under "Totally confident". Personally, if after assesing security risks I can sleep well at night, and if I (and other users) can use the computer without worrying about security issues, I feel totally confident.
The reasons:
Different accounts for different users with different security profiles and personal passwords.
Informed and aware useres.
Updated firewall up and running.
Updated antivirus up and running (resident, e-mail, P2P, messaging and surfing).
Use IE for alternate web browsing and have it protected against hijacking by Spywareblaster.
Netscape as primary browser.
Automatic updates enabled (for the OS and every other program installed that supports the feature).
Updated Spybot installed and resident program running.
Monthly security and program updates, as well as virus, spyware and malware checks.
Don't use any P2P file sharing services (which I have found as a source of problems on EVERY infected computer I have had to clean and repair).
Have disabled e-mail previewieng and configured the e-mail client to filter incoming mail and display them only in text mode.
Am aware of with whom I correspond frequently and, therefore, who are strangers.
Use only legal and supported software.
Protected Wi-fi.

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