Unfortunately, if there was an actual conviction/guilty plea, there's not much that you can do. You cannot expunge a criminal conviction unless you are over 70 years of age or, as absurd as it sounds, deceased.
Your only option would be to request a Governor's Pardon.
Another thought occurred to me. Did you actually plead guilty in 2005? or was it an ARD? If it was an ARD then you could likely get the arrest record expunged. However, as I already stated before, if it was in fact a conviction, expungement is not an option.
Mr. DeMatt's assesment is on target. The other option you would have is to apply for a govenor's pardon. It takes more time, is more expensive and they are difficult but not impossible to get.