Upon installing windows 7 i immediately intsalled avast antivirus and did a full scan. A trojan horse was found in the old vista files which after update have been changed to windows.old, will this trojan horse still be active from there?

Shouldnt be a problem, however the windows.old folder is for older documents and settings...do you already have your important documents backed up? If so you can just delete the windows.old folder.

ye i made a back up before upgrading, its just handy to have all the old files right there. thanks for the reply

What trojan name is it showing, and does it give you the file location of where this trojan is?

i've just deleted it from the antivirus chest, it was win32:zbot-lyk[trj] in my old temporary internet files

Good deal - If it was in the Antivirus chest, it was already quarantined so you're good

thanks