"If we were so concerned about a secular Saddam Hussein secretly making nuclear technology and resources available to Islamic terrorists hell-bent on killing Americans, what do you think a fundamentalist Islamic regime might do?"

More or less what Saddam regime might have done.

"We went to a pre-emptive war against Iraq erroneously claiming he had the capacity to build nukes. So now what are we going to do with the Iranians given that they're actually capable of doing this?"

Well, Iran did NOT have the unique circumstance of having war with us which had resulted in the Iranian signing a cease fire agreement agreeing not to have a WMD program [as described in detail in the cease fire document]. Iran is about the same place Saddam was before Israel took out his reactor.
What if in an alternative universe Israel had instead decided that they did not want to do this pre-emptive strike, what then? Btw, I didn't notice anyone suggesting Israel should have gotten a peace prize for this action.

"Saddam's missiles had a maximum range of 126 miles. Iran has ballistic missiles capable of striking the heart of Europe."

But the Iranian leadership says they are going to nuke Israel, not Europe- don't you believe them?

"So we spend hundreds of billions of dollars and thousands of lives taking out Saddam and we let the Iranians do as they please?!?"

So you bitch and moan about the US enforcing the Iraqi cease fire agreement, but in the case of Iran you think we are failing to do enough to prevent Iran from acquiring nukes?
Note unlike Iraq, we have no proof that Iran was attempting to make nuclear weapons- other than Iranian in leadership positions making statements which indicate that feel they have right to have nuclear weapons and the intention of using them against Israel.

Btw at the moment on CSPAN Daryl Kimball is taking the position that seems likely Iran is 5-10 years from making a nuclear weapon. Kimball is a lefty that if Don were to listen to him would probably think is very well informed. E.g. he is against nuclear technology used for civilian purposes, think Blix is capable of making wise statements, wants America to disarm it's nuclear wepons, ect.