Vista compatibility - fuss over nothing?

Ok here's the deal.

2 Accounts on Vista : "Admin Account" and "UAC Test"

Test 1:
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Login as "UAC Test", create a file in Shared AppData Folder - write some data to it.

Login as "Admin Accout", read file (reading is allowed), add some data and write to disk.

Result : ACCESS DENIED ERROR - File not written.

Test 2:
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Other way around, Created file in "Admin Account", blah..

Result : ACCESS DENIED ERROR - File not written.

Test 3:
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Changed file permissions to "Everyone"

Result : Read and Write access from both accounts.

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