I've just received my new SSD since the old one died. This Intel 320 SSD supports TRIM. For testing purposes, my dealer put malware, err, Windows on it. I want to get rid of it and install Kubuntu on it.

It does not have to be a "secure wipe", I just need the empty the disk in the mosy healthy way. I believe that dd if=/dev/zero of=/dev/sda just fills the blocks with zeroes and thereby taking another write (correct me if I'm wrong).

I've seen the answer How to enable TRIM, but it looks like it's suited for clearing empty blocks, not wiping the disk.

hdparm seems to be the program to do it, but I'm not sure if it clears the disk OR cleans empty blocks. From its manual page:

  --trim-sector-ranges
          For  Solid State Drives (SSDs).  EXCEPTIONALLY DANGEROUS. DO NOT
          USE THIS OPTION!!  Tells the drive firmware to discard  unneeded
          data  sectors,  destroying  any  data that may have been present
          within them.  This makes those sectors available  for  immediate
          use  by  the firmware's garbage collection mechanism, to improve
          scheduling for wear-leveling of the flash  media.   This  option
          expects  one  or  more  sector range pairs immediately after the
          option: an LBA starting address, a colon, and  a  sector  count,
          with no intervening spaces.  EXCEPTIONALLY DANGEROUS. DO NOT USE
          THIS OPTION!!

          E.g.  hdparm --trim-sector-ranges 1000:4 7894:16 /dev/sdz

How can I make all blocks appear as empty using TRIM?