secure file erase on SSD

With ssd's drive levelling feature using different sectors for files, would using an erase program like eteraser's privacy guard and setting it to securely wipe all free space and file slack securely erase any data left over from either ordinary deletes or earlier file erase operations?

XP Pro SP3 full disc encrytpion with truecrypt on all discs Intel e8200 overclocked to 3600MHz

Due to the limited number of writes to the drive, erasure on an SSD is not so straightforward. In addition, many drives fail to implement any way to fully erase something see here. This is contradicted by this with the contradiction noted here. I do not know much about the program that you mention specifically, but I am inclined to say it is not perfect and instead performance depends on the drive in question.

With your SSD's drive-leveling feature, the answer is that there is no easy way to ensure complete erasure (short of nuking the entire drive, and that might not even do it). Rewriting the contents of the file like Eraser does may indeed overwrite the bits in question, but it is just as likely to write the new bits to a new location (leaving the old bits in the old location) and just tell the OS that the old bits aren't there anymore or are ready to be overwritten.

I know of no easy way to ensure safe removal of files, short of zeroing the entire drive, and again, I'm not sure that would work 100%.