Boxed Version and the Trial

I'm currently playing the trial, but I saw the boxed version on sale for a very good price locally and bought it.

Can I use the code that came with the boxed version to upgrade my current trial status? I don't care so much about keeping my trial characters as much as I do my current account name, so if re-installing using the DVD is the way, I will do that.

I believe Ive seen elsewhere that you must first let your trial run out. After that you should be able to use the code from the boxed version to reenable the account and give it the pc license to play.