
So you're entire volume of evidence was based on the contents of one post? That's it? You penned a misleading reply based on nothing but what's posted above? No years of experience? No employment qualifications? No research? No degree in computer science?
'Bob' (not me, by the way), who wrote the first post, used a worst case scenario to exemplify how useful a LiveCD can be. Even if you use it for general browsing, and suffer a malware infection (which, incidentally, is no more likely than using a hard-disk installed OS in the traditional fashion), there is no difficulty in eradicating the malware completely, leaving no shadow of doubt that it is gone. This is achieved simply by re-booting the LiveCD - because the LiveCD boots from a read-only medium, that is, a medium that cannot be compromised.
Of course, as most people with an IQ over 80 would have realised by now, the principal use of the LiveCD in the context of secure internet usage (i.e. free from malware) is to boot and use only for critical functions such as banking. No one is suggesting (except maybe you) that a LiveCD would be used for general web browsing. Whilst there's no technical reason preventing general use, it would be somewhat inconvenient - hence Bob's assertion (and I quote):
"The only way to build a secure machine that's good for on-line banking, etc and is free from (technological) Trojans, keyloggers, etc. is to run an OS off a Live CD that you trust. Even if you get "infected", the infection is wiped out every time you reboot. Of course, this is a pain...".
Bob's reference to "a LiveCD that you trust" means to not just use any old thing you download from the internet. People with experience in this field know that building a trustworthy LiveCD is not challenging, not at all, but requires a modicum of prudence, as would downloading and installing any software. A while ago, in comments for another article on a similar subject, I suggested that a bank could provide a LiveCD itself, pre-configured for that bank. This would provide a good degree of trust for the average user - someone not predisposed to build their own LiveCD - but is certainly not the only way to achieve trust in a LiveCD. And the most important point here, is that any LiveCD from a reputable source that permits web access will be more secure (by several orders of magnitude) for critical functions (like banking).
Has this explanation helped? Do you now understand why, when you said, "Hmm - but it's not very useful if you get infected through the browser shortly before starting an on-line session with your bank, is it? I'll stick to using a grown-up OS, thanks.", that you completely misunderstood what Bob had said, had clearly not bothered to do any reading on the subject and made yourself look rather silly?
And no prizes for guessing what your idea of a "grown-up OS" is!
To save space, read these:
http://en.wikipedia.org/wiki/Telephone#Basic_principle
http://en.wikipedia.org/wiki/London_Buses#Fares