Just use your recovery partition or disk that came with the system, will wipe all your data when you run it.
You may want to be a bit more secure and do a secure erase with a boot disk first, dban works great http://www.dban.org/
4. Go to Explorer, download Recuva and check for any additional personal data left in any of the drives or you could try Stellar Pheonix Data Recovery.
Just use your recovery partition or disk that came with the system, will wipe all your data when you run it.
You may want to be a bit more secure and do a secure erase with a boot disk first, dban works great http://www.dban.org/