PowerShadow is similar to recovery card. When PowerShadow is running, it seems that you are working on a 'shadow' of the operation system. All changes of files on the hard disk will disappear after rebooting the computer. So you don't afraid of virus any more. Here is a screenshot:
The current edition of PowerShadow costs $39.00. If you don't mind the older edition, you can use PowerShadow 2.6, it is free to use. Mine is PowerShadow 2.6. It can be downloaded from my box.net. Click here.
The free registration information is:
Serial Number: VVR29E-R4WCK2-K4T111-V1YHTP-4JYJDD
PS: PowerShadow is not anti-virus software. It can only protect your files from being changed or deleted. It can't guarantee that your private information not to be leaked out.