I will do you team top to bottom.
Catcher: Pudge is a solid catcher, probably the best or second best in the league, especially now that he's running. No problem.
First base: Sexson is a solid option, with lots of upside and tons of power. He's not a stud 1B, but a top 10, solid player at that position.
Second base: Spivey is a little weak, and he came out of nowhere to have an awesome year last year. I'd be worried about whether he can repeat that.
Third base: This is your weakest position. Relaford is hot right now, but isn't even necessarily an everyday player. I would look to upgrade this ASAP.
Shortstop: Rollins is a solid SS, with speed and should have a nice batting average. I would rank him the sixth best SS option behind ARod, Nomar, Tejada, Jeter and Renteria.
Outfield: I would agree that you probably want to see more power here. Everett probably won't keep up his current pace. Once he cools off, he's a marginal starter at best. Matsui looks like he is about the only power hitter in your lineup other than Sexson. Pierre will get you lots of steals, and he, combined with Rollins should keep you good in that category. Salmon will add a little power, but you're still lacking.
Pitching: starting pitchers are your strong suit. Zito, Mulder, and Hudson are undeniably great and should push 20 wins each. Nomo is a solid #4 starter and Loaiza is a nice sleeper, and if he falters you can get someone else off the wire. You lucked out on getting two elite closers in Benitez and Guardado, with MacDougal and Lyon providing plenty of saves. If Izzy comes back, you are absolutely set for saves.
I would suggest trading one of your big 3 Oakland pitchers for a pure power hitting outfielder, since that is what you're really lacking. Try to get someone like Manny Ramirez, Brian Giles, Lance Berkman, Shawn Green, Magglio Ordonez, etc. for one of your top pitchers, because that's where you have trade value. If and when Isringhausen comes back, you may also want to peddle Benitez or Guardado to solidify your offense as well.