The NFL salary cap in a finite thing. While some pundits think Monopoly money is used, you cannot spend over said cap. Period.
As much as fans of teams want to sign the best free agents out there, i.e. - the James Harrisons, Ed Reeds, DRCs, Brian Urlachers, Cliff Avrils, Greg Jennings, etc... they come with a price tag -and you're not going to be able to purchase it at your local Walmart.
All unrestricted free agents are at least four years into their career and with the average football lifespan being about the same average, they're looking for their retirement pension, in theory. So most of the guys that people clamor for- won't be found in the discount bins, they're more like Neiman-Marcus.
Now, the Cardinals could dump Kevin Kolb and his 13 million salary and save 6 mil in a cap hit. Or fellow guards Adam Snyder and Daryn Colledge and their collective 8 mil albatross. Or even watch half of Phoenix commit hari-kari with the release of Larry Fitzgerald and his monster obligation. But how much of this is reasonable, even possible? Even with a Kolb release that puts the team approximately 13 mil under - maybe not enough to sign Carson Palmer supposedly. Nix Snyder and Colledge? Still possibly out the running for Andy Levitre of the Bills.
Arizona is currently 7 million under the cap, little wiggle room, by NFL standards. Will they create more space? That, I'm fairly sure. Will it be enough to sign a top notch FA? That I'm not so confident of. The team and its fans may have to count on "lesser" signings that fall within the cap and below the aspirations.
Because if you try to overspend the salary cap limit - you go straight to jail - with no "Get Out Of ..Free" card.