Wipe Disk can destroy all information in your chosen disks safely and permanently. This function can ensure the security of your private and unwanted data and prevent someone from recovering your data. Once the Wipe operation is carried out by Partition Wizard, the data will not be recovered by any data recovery software. If you use the method of DoD 5220.28-STD, the data can not be recovered by any data recovery solutions.
You can apply this function by click Action Panel -> Operations -> Wipe Disk or Wipe Disk in the Disk menu.
I suppose it depends how paranoid you are about wanting to erase your old data. Unless you are worried about someone rooting through your deleted linux applications with forensic software then a standard format or the "writing zeroes " techniques shouldn't take too long. I've never used Darik's Boot and Nuke - 5 days sound pretty excessive!