I wasn't going to make anymore comments, but being an accountant, I will. The day Worldcom. went bankrupt, is the day/year you should have taken the loss. If it is a substantial amount of money, you can offset some gains in 2003? 2004?, I'm not sure when they went belly up. You may want to ammend that years return.
If it is not a substantial amount of money, you may want to just take the chance and deduct it currently. I don't think the IRS would look unfavorably upon this in the very unlikely event that you got audited. Talk to you accountant.