#1 - Unfortunately you have to give this to the Lakers. Artest is an upgrade over Ariza. We have to assume Bynum will be healthy, and he could very well play up to at least half his potential this season. They will almost certainly resign Odom. Pau and Kobe are not exactly young but still not old enough to be due for any major injuries, so we can assume they will continue to play very well. Their bench is full of young[ish] guys, so if it doesn't get any better at the least it won't get any worse. Simply by virtue of the fact that the Lakers actually improved a little so far this off-season and won it all last season you have to rank them at #1.
#2 - Spurs. This ranking assumes that the Spurs are healthy, of course, but at the moment they are pretty much a complete team, and their off-season isn't even over. They're one big man reserve away from being a solid contender, perhaps even better than the Lakers, assuming that all of their key players remain healthy. That's a big if, though. Nevertheless, they added a quasi-All-Star in Jefferson, had a major steal in the draft with DeJuan Blair, and got McDyess. I will be amazed if they don't end up as the 1 or 2 seed in the West next year.
#3 - Celtics. I put us this low because of what we have not yet accomplished. It's still within the realm of possibility that we don't resign BBD, don't get Grant Hill, and have to rely on guys on our summer league roster to fill in the gaps. We'll be in trouble if that's the case. However, we're one solid wing free agent and a couple decent backups (PG and PF) away from perhaps being #1 or #2.
#4 - Cavaliers. Sure, the Cavs haven't actually gotten worse, per se. But I would argue they have gotten worse relative to the other contenders. Getting Shaq isn't as big of an improvement as the media would like to make it seem. Shaq is knocking on 40 and is a major injury waiting to happen (if not to him then to one of his teammates). The Cavs may very well dominate the regular season - again - but I'm still just not convinced they are Finals material. Getting Anthony Parker is really a wash for them since they're losing Szczerbiak and they've already traded away Pavlovic. The only starting position they upgraded was center and the difference between Shaq and Big Z might not be that big, at least in the playoffs against tough opponents.
#5 - Dallas Mavericks. That's right, I'm placing the Mavs over the Magic. By all accounts it seems that they are going to acquire Quinton Ross, Shawn Marion, and Marcin Gortat, as well as resign Jason Kidd. As long as they stay healthy (they're an older team overall than the freaking Spurs), they could be the #2 or #3 team in the West. Watch out for them. They will probably lose Brandon Bass, but that's no big deal.
#6 - Orlando Magic. You might say 'the mighty have fallen,' but I'm not convinced the Magic really were that mighty in the first place. They got lucky in the East this year. They made their way - barely - past a Celtics team with very significant injuries (re: our best player) and then beat a Cleveland team that had serious matchup problems with two of their leading scorers. They got manhandled in the Finals. If they had kept their nucleus together, they might have been better this year, but the list of players they lost so far this off-season is staggering: Rafer Alston, Courtney Lee, Hedo Turkoglu, Tony Battie, and Marcin Gortat. In return so far they've gotten Vince Carter and Ryan Anderson. Vince may or may not be as good as Hedo, but he's not as much of a playmaker, and he doesn't create mismatches the way Hedo does. The Magic as they are now couldn't hope to beat Cleveland again. The Magic will probably be the 3 seed in the East again, but only because there aren't any other really good teams in the East. What, do you really think the Wizards are going to get higher than 5 or 6? The Hawks? The Detroit Huskies? Fat chance.
That's how things stand as far as I see them so far.