Wow, lol, you dug up not only an old forgotten thread, but, one which we MIGHT have driven just a TAD bit off topic... *whistles innocently* Oh well, may as well go with the flow, at least it's back closer to the original topic in the most important way.
BTW, security issues do exist, but, still something that can be checked for, simply a little harder to do. For example, boot into a linux rescue disc and run ClamAV. In fact, I am distributing discs intended for just such a purpose and even plan to someday get around to rigging one up to actually automatically update clamav on startup, mount local filesystems and automatically scan things for the user requiring no input (currently I have to tell them what to type, though it's still not very much so quite easy for them.) By running completely independant of the host OS, no virtualization processes will be used.
That said, I should add that virtualization isn't exactly the holy grail of virus design either. You see, you can't just put a virus in a virtualized setup and let it go expecting that to be good enough. By existing within a virtualization just for it, it will be unable to do much damage without still interacting with things that antivirus software can catch. I have read of one worrying trick though. Someone pointed out that if they could get it into a rootkit -- essentially running the actual kernel and os itself within a virtualization -- then a virus could exist on the "outside" process and would indeed be very hard to catch (the "inside" process wouldn't even know that less than 100% of the CPU was available even if I'm not mistaken.) That would be troublesome since it would be hard to tell anything is wrong unless the virus goes out of control (and the best virus will not since the moment it goes out of control it risks exposure.) That's where my bootdisk idea comes in.
If you're curious, you might want to try some of the so called "live rescue discs" out there. My personal favorite right now being Finnix but another that was my favorite before it stagnated (it has now come back to life and is fresh with lots of updates) would be the System Rescue CD which is equally good compared to Finnix probably (depending on what you want to use it for.) I believe in both cases they should recognize any onboard or external network interfaces, use DHCP (assuming your modem supports it of course) and provide internet access (don't worry, iptables -- the linux kernel firewall -- is built in.) I think you should be able to just type freshclam and get updates right off, then mount /mnt/hda1 or whatever your harddrive and partition may be and start scanning. (ClamAV, by default, should just report any suspicious files without taking any action, leaving you to do what you wish with such files unless my memory is failing me -- sorry, it has been a while since I found even a false positive on a virus.)
Of course, if you have an unusual connection type -- such as a built-in DSL card (not network, but, an actual DSL card where the software must dial in for you and everything rather than an external modem handling that for you) -- or if you have a dialup modem, you will have to still configure things. A proper cable or dsl modem should come with a DHCP server built-in, though maybe some will be disabled by default. Any router worth it's weight in salt definitely will. Also, wireless cards are, admitedly, not getting very good support in linux right now, so I wouldn't depend on one of them to work on such a rescue disc (but then, considering how unreliable they can be sometimes, you should always have the OPTION of a fallback to an ethernet card for an emergency.)