@Gene O wrote
Secure erase will free all blocks by applying a voltage to the substrate of the blocks. For reinstalling, optionally do the secure erase followed by creating the partition and performing a quick format. You may want to do SE depending on whether your controller supports TRIM or not.
Windows is aware of SSDs (as long as they're not connected as part of a RAID volume) and it issues TRIM commands as appropriate. If you use the Windows 7 install disk to delete all of the partitions and recreate a new partition for the OS, Windows 7 will issue the TRIM commands necessary to let the controller know that all of the blocks in the drive have been freed. That's effectively the same as doing a Secure Erase.