Your welcome.
Spybot S&D and adaware are lightweight (IMHO) when compared to these anti-spyware applications.
SUPERantispyware On-Demand only in free version. Or
AVG anti-spyware (formerly Ewido) Resident scanner during trial On-Demand after trial ends. Or
Spyware Terminator Resident scanner.
I don't know how this other detection was found in the System Volume Information folder as that is usually associated with a deletion or moved file from the system folders and if that were the case I would also have expected you to have had an avast alert on a file in the system folders first.
It may be worth clearing all the old restore points and creating a new clean one (assuming your system is currently clean other than this detection).
Create Clean Restore Point - Clear old Restore Points.
Now you are clear of infection create a clean System Restore point:
1. Click Start, All Programs, Accessories, System tools, System Restore.
2. In the pop-up that appears fill in the radio button to Create a Restore Point
3. Click NEXT
4. Enter a useful name that you will remember if you need to find this again (Clean Restore Point)
5. Click CREATE
You now have a clean restore point, you should clear the old ones:
1. Click Start, All Programs, Accessories, System tools, Disk Clean Up
2. Click OK on the C: drive
3. Click the More Options tab
4. In the System Restore section click the Clean Up button