I have been a long time windows user till about thanksgiving when I switched to ubuntu. on windows I used firefox because I could trust the security that it gave. Since malware/virus are next to none on ubuntu (and yes I have read up on all of the diffent point of views on both sides of having ubuntu security software or not) is google chrome just as safe on linux or should I stick with firefox?
from my experience, as an average user I would say you don't have to worry so much about malware on linux than on windows. This might be very different if you are running servers with important content on it. Since you have to approve anything that could be harmful to your core system (ie. anything that happens outside of /home) by giving your root password malware can't really affect your system settings, unless ofcourse you unknowingly grant them access.
So just stick to the rules...only download executable packages from trusted and/or well reviewed sources and NEVER run wine in sudo mode^^
Regarding the browsers I'd say either one is fine. I've used firefox for 3 years and I am now using Chromium for about a year and a half and I have never had problems with facebook hacks or anything like that.
From a very subjective point of view...I like the user experience with Chromium a little better though.
This is really a matter of opinion as you're correct in that there aren't as many viruses or malware written to target Linux based operating systems. Of course, that doesn't mean that there aren't any either.
If you're concerned, maybe just install something like Avast and at the very least you've got some decent virus protection for free.
So it's up to you and your comfort level. In terms of a browser, I recommend Chromium as it has sandboxing for the web browser rendering services which are really quite good.
Check out the Chromium security principles. Nice piece of mind as well.
Linux is not invulnerable and there are cross platform vulnerabilities.
Check out http://www.ubuntu.com/usn for firefox vulnerabilities as well.
At the end of the day, you need to match your security with the value of your assets on your computer or the sites you connect to.
There are some common protection you should do on any OS, for example you should only conduct financial transactions on an encrypted connection, ie https
Considerations for Firefox on Ubuntu would be:
1) Enable the apparmor firefox profile.
sudo aa-enforce /etc/apparmor.d/usr.bin.firefox
2) You might want to use NoScript. Only you can decide if the hassle is worth the additional security.
3) Social engineering ( Phishing ) is often more effective then cracking and works on any os.