Monty,
Though I'm not a CP guru, still I would mention collect the tax transcript - it's available free of cost.I'll taking them with my tax returns while appearing for interview.My common sense says,tax transcript is more authenticated docs than tax returns - as the later is a prepared by u or by ur tax-consultant and the former is directly from IRS itself.
For tax transcript, call 1-800-829-1040 - it's automated service and pretty simple too. They will send ur transcripts within 10-15 days.
cheers!!
Ranen