How frequently does Apple release security patches for Mac OS X?

Those three trojans are only affecting Windows, as stated by Sophos here, here and here (found via www search engine, and probably via clicking the names of the malware in that window in your second screenshot). Is Apple responsible for your surfing behaviour and should protect users from Windows malware, which in no way can affect Mac OS X?
Btw, Mac OS X 10.4 Tiger is no longer updated with security updates for quite some time. Since Mac OS X 10.4 Tiger is five Mac OS X versions ago, Mac OS X 10.5 Leopard, Mac OS X 10.6 Snow Leopard, Mac OS X 10.7 Lion and OS X 10.8 Mountain Lion were released after that, you will probably not see any updates for Mac OS X 10.5 Leopard and maybe not even Mac OS X 10.6 Snow Leopard. Mac OS X 10.7 Lion might still be in the mix though.

Sophos should be avoided, as it could actually increase your Mac's vulnerability, as described here, here and here.

Currently there are zero viruses affecting Mac OS X in public circulation, but there are other kinds of malware existing, that can infect your Mac.
To learn more about malware in Mac OS X and what steps can be taken to protect yourself, read the following F.A.Q.:

LOLZpersonok said:

Oh okay, thanks. I'm a bit of an idiot, I actually thought Mac OS X 10.4 was still receiving patches. Wasn't the Flashback thing a trojan or something? I'm not sure though, but can it infect OS X 10.4.11? I haven't looked at the links you sent me, I've gotta go pretty quickly but I'll do so soon.

And, even though they're Windows viruses, it's always better to be safe than sorry. 'Cause you never know. I wish I could install Kaspersky on my Mac though, I have it on my PC and I haven't had a virus problem with it since.

But thanks anyways.

Click to expand...

Please read at least the bolded MALWARE link, as it explains, what a trojan, what a virus and what malware in general is. I have used Mac OS X since Mac OS X 10.3 Panther and have run Sophos for one month during the past eight years (to test the **** out of it). I have never installed any malware on my Mac during those eight years and all that Sophos could find, was Windows malware, which cannot affect Mac OS X (you cannot run Windows software on Mac OS X (except in a virtual environment or with WineSkin or something similar)).

If you are really unsure about malware and want to be safe, use ClamXav, it is free and not as intrusive as Sophos. And please read the MALWARE link.

PS: The malware found on your Mac are NOT viruses, one is a trojan, and the two others are suspected to be some malware (suspected means in this case, they don't really know, only that that software behaves suspiciously ).

Again, there are currently zero Mac OS X viruses in public circulation, and the handful of trojans out there can be avoided using commons sense and employing safe browsing steps, which are outlined in that MALWARE link.