Which '08? Early 2008 or Late 2008 (aka unibody)? The Early 2008 model uses 667 MHz PC2-5300 DDR2 RAM, the same as the MB - so, those sticks can be used to upgrade your wife's machine. The unibody MBP uses 1066 MHz PC3-8500 DDR3 RAM, and that cannot be used in the white MB (but is correct for the new unibody MBs).
Which '08? Early 2008 or Late 2008 (aka unibody)? The Early 2008 model uses 667 MHz PC2-5300 DDR2 RAM, the same as the MB - so, those sticks can be used to upgrade your wife's machine. The unibody MBP uses 1066 MHz PC3-8500 DDR3 RAM, and that cannot be used in the white MB (but is correct for the new unibody MBs).
4 GB is the 'official' Apple limit. Many users have reported that installing a 4 GB stick + a 2 GB stick works. However, 8 GB is not possible on the 15" unibody MBP (although 8 GB is supported on the
17" unibody MBP).