Hi,
security is a broad concept, if you are using online banking, you need to make sure that there is nothing special about it that would need Windows drivers or special hardware like a card scanner.
There are indeed a few viruses out there but the biggest worry you would have is someone trying to hack your bank account!!.
Linux is secure within the bounds that as long as you leave the system in user mode only and don't surf the web as root user, you shouldn't have any problems, I have been using Linux for years and have never had a virus.
I use "Browser Protect" which is a FireFox add-on and it suits me fine!!.
See the links below if you want an on-demand free anti virus scanner for Linux:
viewtopic.php?f=6&t=1948For a 32 bit version only (
no 64 bit version available) from Avast:
http://www.avast.com/linux-home-edition#tab2Regards Wolfman