Eliana, unfortunately, after performing some tests on my end, I don't think the Snow Leopard "Reset password" approach is going to work. Here is what I did:
I took one of my existing user accounts and turned ON File Vault for that account.
Then booted up the Snow Leopard DVD.
Selected "Reset Password...".
Interestingly enough, it allowed me to create a new password for the File Vaulted account, WITHOUT asking for the Master Password.
Unfortunately, when you attempt to log into the account again, the system detects that the account password has been changed and no longer matches the File Vault password. So it asks for the old password before allowing you to log into the account.
Sorry, it doesn't look like this is going to work.
http://docs.info.apple.com/article.html?path=Mac/10.6/en/8739.html
+"If you are the administrator of the computer, and you can't remember the master password, the information in your home folder is lost forever."+
http://docs.info.apple.com/article.html?path=Mac/10.4/en/mh1909.html
So it appears that without the Master Password, you are not going to get into the File Vault account. I am so sorry. 😟