Loren wrote It seems that iTunes remembers the Apple ID with which each tune is purchased.

It is not only possible it is by design Apple keys or tracks all purchases to a specific Apple account. You can create a second account have your purchased spread around - that is not unlike two people with different accounts using the same PC. If you want to change your Apple ID because you change your Email, you need to specifically do that. (I recently did that and the process is not intuitive.)

If Bill actually did this, I strongly suggest you contact Applecare ASAP. Apple's official policy is they do not merge accounts. But given this situation, I expect you are more likely to get someone to accomplish the account merger you need.

Gordon
Atlanta