My serial number is stuck in a dead computer

Even if you were able to do it, you won't be able to activate it on a new computer, since Adobe retired the activations servers for this version a while ago, so it doesn't really matter.

@hua_0282 that's going to be hard for Adobe to do anything especially if you didn't register Acrobat Standard XI. I know when I had CS5, 5.5 and 6.0, I had them all registered. If by chance, if you still have the original CD's or was it a 'download?' If it's a download, maybe look in your emails if you still have that original email with the serial number.