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I'm guessing that there is no real problem and that the reason the beta fails to install is that it checks for version 10.5.6, which with 10.5.7 it obviously doesn't find, so installation cannot proceed.

Apple are probably putting it in the seed notes so that people know that it won't work. The next Safari beta will fix this.. if I'm right, that is.

This seems extremely likely to me. If you read the seed notes you can see that stuff unrelated to Safari is getting fixed in each build.
 
I am currently using a white Santa Rosa MacBook 2.2. I bought a white Nvidia MacBook 11 days ago, and tried to swap my old hard drive into the new one, and it came up with many errors. That is because the 10.5.6 build on the white Nvidia MacBook is a special build, and not a universal boot build like the 10.5.6 Build 9G55 which is on my white Santa Rosa MacBook.

I'm using an aftermarket 7200 RPM drive, and that's why I don't want to use the stock drive.

Please don't tell me to just use Migration Assistant or any of that stuff. I only do clean installs, and don't want to go through the hassle of reinstalling everything. That's why I really need 10.5.7 to come out, so I can update my OS, and just swap my hard drive into the new white Nvidia MacBook, and immediately start working.
 
I am currently using a white Santa Rosa MacBook 2.2. I bought a white Nvidia MacBook 11 days ago, and tried to swap my old hard drive into the new one, and it came up with many errors. That is because the 10.5.6 build on the white Nvidia MacBook is a special build, and not a universal boot build like the 10.5.6 Build 9G55 which is on my white Santa Rosa MacBook.

What build does your Nvidia whitebook have?
 
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