What Republican are you aware of "that has a decent track record on immigration" and is a potential candidate for president in 2008?
Immigration is not my primary issue. Ask me about judges, and I'll run off a list of names. It's the responsibility of people that consider this their top issue to vet candidates that conceivably could win that have at very least a tolerable record. You cannot tell me there isn't one Republican, aside from Tancredo, that would seek to do right by the issue. Though if you seek a perfect record you'll doubtless be disappointed.
Further, I turn the question around. Name me a Democrat with a good record on immigration. This is my point. Hillary thinks rhetoric with actions in defiance of that rhetoric will win an election. It will not. She'll have to offer teeth in form of passed legislation otherwise she has nothing. She isn't running against the Bush Administrations record. She can try to run against the GOP's record, but the Democrats have a worse record.