I've tested two different models, both worked fine.
Even a 320GB one which needs a lot of power.
I don't think you can go wrong.
I would pick a nice casing 2,5 inch, aluminium. And pick a good harddrive inside.
If you want maximum performance pick a 200GB Hitachi 7K200.
If you want maximum capacity pick a 320GB 5400 RPM like Samsung or WD.
If you want low powerconsumption, high capacity and low price, pick a 5400RPM 250GB, like a Samsung or WD for example.