...and, something else to keep in mind is whether you really need FileVault or not. Sure, it's cool to be able to say your data is encrypted really well, but what's more valuable to you -- the data on the hard drive or the computer itself? If it's the computer, I would put more effort into locking the computer down physically rather than trying to encrypt data that isn't sensitive. If you store school projects or images you made for fun or Word documents or anything like that, you don't need it. If someone else gets their hands on those files, it really doesn't matter, plus password-protecting your computer by way of a login password is sufficient enough to protect those files. However, if you store your company's financial records and sensitive employee information and sensitive company documents, you need it -- theft of those files could bring a company/individual to its/their knees very quickly if those files got into the wrong hands.
Have you tried DiskWarrior or Drive 10 to try and recover deleted files?
