but we have intego virus barrier x6 so why didnt it get picked up?
Intego or you may not have updated its malware defintions. You can't really trust AV programs to protect you. They give people a false sense of security.
It appears it may be "phoning home," contacting its author with some data -- no idea what -- from infected machines. I would change important passwords immediately and never use the same password for different occasions.
how do i know its really gone?
I don't know which directions you followed to remove this (I'll give you mine, below), but you probably got everything; it's not that complicated to remove. You could do a full drive scan with ClamXav. They appear to be staying on top of this. But this thing keeps using different names, so don't know if that leaves holes in ClamX.
http://www.clamxav.com/download.php
If you gave your credit card #, contact them and dispute the charges and cancel the card ASAP.
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First, restart in Safe Boot by holding the Shift key down at the chime. Or, alternatively, open Activity Monitor in Utilities, set to Active Processes, find the program and force quit it. This will keep it from running, but only temporarily, so you can remove it.
1. Drag the MacSecurity program -- or whatever it's called; it keeps using different names -- MAC Defender, MacProtector, MacKeeper 911, Apple Security Center (installed in the Applications folder by default) to the Trash. Empty the Trash.
2. Remove item of same name from the Login Items for your Account in the OS X System Preferences (if it exists).
3. Go to your Home folder Library>Preferences and Application Support (may not be anything there, but check just in case) and search for any files with one of the above names and trash them. Empty the trash.
4. If you use Safari, go to Preferences>General and UNCHECK "Open "safe" files after downloading. Keep that unchecked.