It depends on the OS and the SSD.
Some SSD's will support the "trim" command. That command allows the SSD to release free blocks without having to do a rewrite. That improves performance and increases the longevity of the drive. Intel X25-M gen2 has the capability, while gen1 does not.
If you have windows-7, it is capable or passing the trim command to the SSD provided that the ssd is in SATA AHCI mode. You will then get the windows AHCI drivers.
If you install in IDE compatibility mode, or raid, then you will get motherboard drivers which currently do not pass on the trim command.
For a clean install, you might want to reformat, but I see no need for a secure erase which will beat up your ssd for no good purpose.
I think it is better not to use raid for a SSD. I tried raid-0 and found that while HDTACH runs were impressive, actual performance was not improved.