How can you identify if a Trojan Horse has damaged your computer?

[JG]

My computer detected a Trojan Horse on a file I had since long ago, and I had previously scanned it and the antivirus found no problem.
There appears to be no data missing on the computer, nor has it behaved in a strange way. How can I know what did the Trojan do, if it did anything? Could the antivirus program be mislabeling the program?
PD: I use symantec antivirus
Yes, of course. I update it daily.
I already deleted the Trojan.
But there doesn't seem to be anything wrong with any bank accounts.

[tempo1]

At the worst a trojan can steal your social security number, your passwords, your banking and fiancial information. Identity theives love this stuff. It brings good money on the black-market.

Trojans, these days seldom vandleise a computer, they are coded to do their dirty work silently.

I suggest that you get a 2nd opinion by scanning with a good anti-spyware.

SUPERAntiSpyware:
http://www.superantispyware.com/

It comes in a free version and is very good in detecting and removing trojans.