I agree with sonofdon fanboys are not needed
Name calling won't help. I have discovered over the years that anger is the worst enemy of troubleshooting. Unfortunately, I've also discovered that suggesting that people put aside their anger tends to make them angry. Ironic isn't it.
I do not discount your problems. My personal Macbook is still 10.5.8 (which connects great) even though I have a SL upgrade on the shelf. That's why I'm following this thread. But I also manage SL laptops that are doing okay.
There are problems with newer Macbooks. It's likely several problems, including the firmware of the new airports (my prime candidate). Everything I know to try is somewhere in this thread though some steps are drastic and difficult. Some might have to be done in a particular order. At one point, I tried to make a checklist to help, but I lost track after 10 items.
If it helps, here's my experience so far. I currently manage one new Macbook, one Snow Leopard upgraded, and one 10.5.8 Macbook that all appear to be working though the newest system took a bit of coaxing at initial setup. The problem with the newest system seemed primary related to dropping DNS. It also does a bad job of scanning the Windows workgroup and LAN domain names, something the 10.5.8 system never had trouble with. Setting DNS servers manually solved the DNS issue. I have not solved the Windows/domain networking weakness. I believe this is simply a new incompatiblity with my older server (which I can't upgrade) so I work around it (low priority). I also had a serious Samba compatibility problem with both Snow Leopard and a new Windows Vista machine. The solution to that was server side (deleted old ".dsstore" files on the server that cause SL problems for some reason). Oh, the Windows Vista machine required a registry hack if you care.
I am sympathetic. And I am trying to help. And now I'm cluttering the list with unecessary blather, so...
Cheers,
tod