I don’t often “recommend” software but there are two critical bits of software that everyone needs a good anti virus and good backup.

For the anti virus I take the bold step of recommending AVG Free and for backup I just found out about GFI Backup…

GFI Backup for Windows handles traditional folder and files backups, but it also has special options for backing up your registry, email, and program settings (including setting for programs like Skype, Putty, Photoshop, Dreamweaver, Winamp, Firefox, IE and Opera).

Backups can be saved to CD/DVD, removable drives, LAN folders, or remote FTP. Scheduling, compression, and AES encryption are also supported. For those who use an external hard drive or a NAS, GFI can also handle synchronization tasks.

Related links:

Free GFI Backup Home offers powerful-yet-simple backup and sync