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I just installed the western digital 120gb 5400rpm sata hdd from Other World Computing (macsales.com) and it works perfectly. I havent noticed any difference in heat and noise from the stock 60gb seagate. It went for about $149 which is alot cheaper than the only other 120gb hdd that is available from seagate.
 
I just got a 100GB 7200 Seagate (also 2GB of RAM) from OWC and I was very pleased. But I have also ordered from Newegg in the past and have been pleased.
 
I also ended up purchasing a 120GB 5400RPM Western Digital drive for my MacBook at OWC (macsales.com). I've had good experiences from them in the past.

I also purchase hard drives from www.zipzoomfly.com. They often have the least expensive prices on equipment (usually less than newegg.com) and decent customer service.

I think purchasing from either of these three retailers (macsales, zipzoomfly, or newegg) will be a good bet.

--As a side note, most drives from zipzoomfly ship 2nd day for free.
 
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