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I assume you download applications from web sites. Do you just blindly assume they are clean? >>
Only Microsoft corporation.

No I don't assume so and I don't have time to play so I don't shareware and only download *usually* from major vendors when I need something. Even if something does have a virus my understanding was it's new and can infect vaccinated computers. So it's just not woth the subsription to me. I regularly have 3-4 ghosts images and all data files on a separate volume..
I ghost when the OS stats acting buggy which does happen to me at least every 6 months. It could be virus I don't know. But it helps for another 6+ months before It time again.
Image 1-
Microsoft OS
All hardware drivers
Image 2
Above+
All commercial applications
Image 3
Above+
All freeware, shareware etc.
Image 4
Above+
Network config, and user settings etc etc.
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Furthermore, you never open any documents from colleagues or download any files from any other sources? >>
I regularly send and recieve email, word, autocad, pdf files to clients and colleages. NP. Yet.
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Any Winblows PC that accesses resources on the Internet, and saves any of them locally, shouldn't operate without some level of virus detection. >>
fair enough, I think it's wishful thinking that you'll or macaffee will stop it.
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While a real-time scanner does consume CPU cycles, you're mistaken on how much of a hit this is. It should be negligible on any 500 MHz CPU or better. And if the hit is that much of an issue on an older PC, you can use the demand scanner only. Also, besides the initialization of a real-time scanner, anti-virus software doesn't add any time to boot-up. >>
I have used them even recently on a t-bird 1.4 running XP. They do a scan upon boot, and promt you regularly for backup scanning stuff, and whenever I tried to download it scanned. Just over all an intrusive hassle which I 'did'nt care for so I uninstalled it.