I have a 2008 MacBook Pro. NetBSD 7 amd64 (netbsd-7 stable branch, but all versions I have run are ok ) works mostly fine, except that I am having problems with wifi, both the builtin athn, a TPLINK USB urtwn0, and a USB rum0. So I would say try it, and see how it goes. Once you are ok with wiping the disk the install is easy, especially if the machine is so old as to actually have a CD drive. I am also running NetBSD 7 i386 with almost no issues on a 2006ish white MacBook. I didn't try i386 on it; I wanted to have a pkgsrc build machine for each architecture. (I don't run X11 because both of these machines have problems; one has a stuck mouse button and on the other the U key is flaky. But that's not about NetBSD and made them free to good home. :-) A machine that old surely has 4 GB or less. So running i386 mode wouldn't hurt that much. But try amd64, and please report back for the archives.
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