No, Sony made it rather easy to upgrade the HDD by design. After all, they are pushing use of their PlayStation Network where you can download videos, game demos, etc. Some of the first PS3s only came with a 20GB HDD. Even the 320GB models are likely not going to be enough for some people.
And people have been replacing the HDDs on their PS3s for years, nothing bad has happened AFAIK.
considered jailbreaking/modding/hacking a PS3? I was thinking about upgrading the HDD, but after reading this,
http://www.joystiq.com/2011/01/11/report-sony-could-remotely-disable-jailbroken-ps3s/
I do not want to take any chances.
Thanks in advance.

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