Harden's a top SG in the league. He put some big numbers last season at reasonable efficiency in his first season as the man, with only Parsons to take pressure off, even though the entire league knew of his talent, so he wasn't sneaking up on anybody. Depending on how things shake out with Wade's aging and Kobe's injury/aging, Harden could well be the best shooting guard in the NBA come April. Harden and Howard is a worthy tandem, on par with McGrady and Yao. Parsons is a worthy third wheel. With the roster filled out, that's a top 4 team in the west, for sure.
Houston's achilles heel last season was their defense. Dwight by himself helps a lot to address that, seeing as he's one of the better defensive anchors to ever play in the league. If the Rockets add Josh Smith via S&T, which they certainly have the means to do and has been rumored for a while (for Asik), you can add another elite level frontcourt defender to that mix. Now you're a championship contender. If that goes down, I have them coming out of the west next year.
Daryl Morey already deserves next year's executive of the year award. The Rockets appeared rudderless and mediocre ever since Yao went down in the 09 playoffs. Last fall they turn it around by capitalizing on OKC's impending cap hell and stealing Harden, now they pull Dwight and they have assets left over to maybe add one more guy they need.
The issue now is whether Dwight will grow up and stop disrupting everything. You'd think he will, since he chose his destiny here and free agency is no longer looming, but after the way he's handled himself over the past year and a half, who knows. His personality is disturbingly similar to Manny's.