Quick version: It ain't pretty:
There is less money remaining on Oswalt's deal than Haren's deal, but Oswalt's deal offers a shorter-term pain point, and his salary for 2011 really would be $18 million -- if you include the $2-million buyout for that option. There are reports, and have been for awhile, that Oswalt wants his new team to exercise the option before he'll agree to the deal...
...Whether or not the 2012 option is exercised the Cardinals are looking at a rotation with Oswalt in 2011 that would cost $50 million.
Hard to see how they fill out the roster with a $100-million budget.