Whenever you find trojans on your system nowadays, expect havoc to be had.
Even when you remove them, they can leave trace programs that act as reinstallers and/or generally malicious spyware.
What kind of trojan are we talking about? Check sarc.com's free threat explorer
http://www.symantec.com/norton/secur...rer/search.jsp and find out exactly what your system had.
If it was a keylogger, then change all passwords on another secure system, wipe and reload. Then again, it may have been something simple like a redirect script.
I would dare say that 70% of my company's service calls at the end of December were Virus/Malware related. That's significant.
Everyone needs to beef up their antivirus/antispyware/antimalware suites AND be careful of what you click on, open up or visit, regardless of the trust level.