Antivirus detected a trojan horse but can't remove it

[Jacob.d]

My antivirus has detected a Trojan horse: PWS-LegMir installed in the directories
Windows/System32/Conime.exe
Windows / WinSxS / etc Conime.exe

He tells me he can not remove them.

1) Are they dangerous? Is that the reason for the slowness of my system (Vista computer)
2) What do I do?

Thank you for your help.

[arturro]

Try to restart your system in Safe Mode and delete the virus files where your anti-virus found it.

[Jacob.d]

Thanks but two questions:
1) If the file is essential then?
2) I just turned on the antivirus again, it does nothing.

[arturro]

Probably put in quarantine, it will get disabled and will not affect your computer.