Is formatting the harddisk completely really effective in removing any and all types of viruses on it?
It depends. There are different types of formatting. Some will completely erase everything on the disk – even the information in the boot sector where some viruses can be found. There are other “short cut” formatting options which may not totally erase everything. If you indeed want to start from a totally blank disk, then you should delete the main partition which should be an option at the beginning of the reinstall of the operating system. Then tell the system to create a new partition and perform a total format of the partition upon which the operating system will be installed. And make sure you reinstall the operating system from the original CD and not from a backup since a virus might be in the backup copy.
