You have the following scan options:
Home
Your Home folder is the default area on your computer where you save your documents, pictures and photographs. When you choose this option, Virex scans other folders too, for example, your Desktop, Documents and Public folders. After installation, Virex automatically scans this folder the first time you launch the software. This feature is enabled by the Automatically scan at login preference.
Documents
Desktop
Public
The Public folder is where you can store files that you want other users of this computer to see.
Applications
The Applications folder is the default area on your computer where all its software packages are installed.
Macintosh HD
Macintosh HD is the computer's hard disk. Choose this option when your computer activity is low as it can take some time to complete.
All Local Volumes
Local volumes are defined as any ZIP drives, floppy disks or CDs mounted at the time of the scan. Local volumes does not include network drives. To scan a network drive, use the Choose... option and navigate to the area that you want to scan.
Choose...
You can select which area on your computer that you want Virex to scan, for example, your iDisk location. To scan your iDisk location, you must know your iDisk user name and password.
This information and more can be found at http://virexhelp.com/