1. Some nice friends in the Mac community released a tool so you can check if your Mac is infected with the Flashback trojan. This tool works on Mac OS 10.6 or 10.7. If you are running Mac OS 10.4 or 10.5, you need to think about doing one of two things
A) Disabling Java completely (may impact some functionality of your Mac)
B) upgrade your Mac OS, or if that’s not possible get a new Mac
The tool to check your Mac for this virus and this virus only can be found here http://c-mac.me/Fc21
A file will download to your Downloads folder or in some cases a location of your choosing. Downloads folder can be found at Finder >> (Home Folder) >> Downloads.
Double click on the file, which then creates a folder by a similar name. That folder has two files in it. Open the first file, which will test your Mac. Then after it is finished, open the second file which will test your Mac again. If you come back with any problems found — then its time to develop a plan of action for the present and future.
2. To see if your Mac has Java installed in the first place:
Go to Finder >> Applications >> Utilities
You will most likely see an icon for Java.
This is not bad in and of itself and not an indication of a virus.