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this is an external drive, meaning its meant to connect externally to your mac via USB/firewire/whatever cable it uses. Although the drive inside the enclosure will work internally in your macbook.
 
I just upgraded my MacBook Pro with and Seagate MomentusXT and it is much faster than the Western Digital Scorpio (500GB) i had before.

The MomentusXT is a bit more expensive, but it almost feels like an SSD and you can get a 500GB without selling your car to afford it :)

Before my MBP used about 50 sec to boot, now it boots in 30 seconds!

The only downside is that it is slightly more noisy, but not that much that it's bugging me.
 
this is an external drive, meaning its meant to connect externally to your mac via USB/firewire/whatever cable it uses. Although the drive inside the enclosure will work internally in your macbook.

It's actually a kit meant to replace your hard drive and put your old one in the enclosure.

For OP, yes that will work. You probably won't notice any difference in speed, as it is the same speed as the stock drive. If you need space and want more speed, go with a 500GB 7200 RPM drive, like the WD scorpio black
 
It might be a bit faster since the 750GB one will have a higher areal density.

However, if you want to see some significant speed increase, you should get a 7200RPM drive.
 
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