I have an existing PHP script that needs to work with data from an Access db, and the machine it's on is migrating from Win2K to Windows 7. I looked around, and Microsoft seems to say that this is still available somewhere, but I can't find any solid information about how to actually get it.
It is not an option to migrate this to another db at the moment because of other dependencies.
Did you actually Google "get jet odbc driver for windows 7"? I did and I found a number of possibilities, though only one of them looks like it will work.
First off, keep in mind that Jet itself has shipped as part of the OS starting with Windows 2000, so all you need are the ODBC drivers themselves.
The third Google link, Information about Jet 4.0 Service Pack 8, allows you to get the Jet ODBC DLLs (you'd need to get the version for NT4). I worried that this installer might check the OS and prevent you from installing the files, but it just runs transparently on WinXP (I'd assume the same on Vista/7, but maybe not). Since the Jet files are protected OS files, there's no danger installing an older version (a computer that's been kept up-to-date with Windows Update will already have something higher than Jet SP8, but the ODBC drivers are apparently not shipped with the OS in Win7, so this should work). If you can't get them, I can install it on my old Win95 box and send you the ODBC-specific files.
You may also have to install MDAC 2.8 to make them work (though you could register them manually, there are still non-Jet ODBC files that are needed that may or may not be installed on Windows 7). So far as I can tell the MDAC 2.8 download will be required.
One last caveat, if it's 64-bit Windows 7, you may be out of luck if you're using the Jet ODBC driver from contexts that cannot use 32-bit components. There is no 64-bit Jet yet (that's coming with Office 2010, and is in beta). A recent SO discussion has the link to the beta of the 64-bit Jet drivers. I don't know if that includes 64-bit ODBC support or not, though I'd tend to think it doesn't.
Use odbcad32.exe under %WINDIR%\SYSWOW64, you will find all the 32bit drivers enumerated. I'm sure MS Access 32-bit ODBC driver is shipped.