Disclaimer: I'm probably much higher on Harden than most Thunder fans, but it's not a homer thing, as I've argued that Ibaka is presently overrated (I love what Ibaka brings to the table, but his finishing 2nd in DPOY voting is a joke IMO). On a related note, you can see a lot of our arguments about Harden's value (at least relative to Ibaka) in this thread from last month.
I think Harden is an absolute star: at least Top 25 right now, and a few years away from being Top 15. I wouldn't considering trading him for a package of lesser players. Thus, as far as Minnesota goes, I wouldn't consider trading Harden in a deal that doesn't involve Love (which doesn't make any sense for Minnesota) or Rubio (which doesn't make sense for either team). I really like Pek, but ultimately he's just a role player. Williams still has a lot of potential, but that's all he is right now; otherwise, Adelman wouldn't have trotted out the horrific duo of Wes Johnson and Mike Beasley at the 3. He doesn't even have a position, and he wouldn't get a lot of burn on a team that already has Kevin Durant at SF and Serge Ibaka at PF. Williams is a huge gamble that could pay off for the right team, but to have any chance of reaching that potential, he needs to be on a team that can give him a lot of minutes. A contender with OKC's current personnel doesn't make sense.
Perkins' contract isn't going to result in a Harden trade. Perkins would get amnestied before Harden (or Ibaka, for that matter) is moved for financial reasons. Thus, the economic impetus for a Harden trade is moot.
"And you'll get arse from me every single time you spit on krstic."--krstivoje