Bugbear is particularly nasty, as it contains a keystroke monitor, which it uses to log everything that you type to disk and subsequently email them to various addresses. This can (potentially) pass on all your password, credit card details, etc., so anybody who has been infected by this virus should probably assuem that all the passwords that they have used have been compromised and should be changed. Likewise for credit card, bank account details, etc.
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To protect against this, and other "Trojan Hoirses" you might want to consider installing a "firewall" product, as well as an anti-virus product. This analyzes connections both to and
from your system. This will enable you to spot unusual or unexpected connections from your computer. It's quite entertaining (and frightening) to watch all those "innocent" programs going onto the net to lookf for updates, etc.
I've had good experiences with TinySoftware's produtcs in the past, which used to be free for personal use, but I see that now they are commercial only (see
this thread) for more information.