How can I enhance security from malware (passwords, permissions, Wi-Fi router)?

[m654321]

Recently I posted on the LL forum that I had been hit by the partner18mydomainadvisor, by inadvertently visiting its .com website, when I had only wished to look up information about it. To cut a long story short, I reformatted by hard drive, and clean installed LL2 again.  Problem sorted.

However, the experience made me ask the question about how secure my set-ups are, i.e. a win7/LL2 dual-boot and a  distro-only multiboot).  Since I came to Linux I have always been a paid subscriber to the ESET antivirus version for Linux (having had very good experience of this with previous MS Windows only set-ups) to take care of general security, together with the usual regular updating of LL2.  I should add that I am a home-user, and sole user of the laptops concerned - I do not use the laptops in public spaces.

What about passwords?  This made me look at the three instances when a password is needed in any given session...
(1) LL2 logon - a password was set-up when installing the OS (I have set LL2 to auto-logon when booting up)
(2) Making changes to the computer - a password is needed (permission requested) when say installing new software with synaptic package manager
(3) Keyring for Wi-Fi - a password is requested for the keyring default, whenever I use the Wi-Fi  after auto logon

I then realized that the password I set up for (1), is the same as (2) & (3)!  Doesn't this render my LL set-ups vulnerable to malware attack?

My question is, should I have three different passwords for LL2, one for each of the above three instances?

Any advice on this gratefully appreciated - many thanks ...

Regards
Mike