Some important details:
1. You cannot simply take the current hard drive and put it into the newly acquired PS3. The new PS3 would not be able to read that drive.
2. You cannot use the backup utility on the current PS3 and restore that data onto the newly acquired PS3. A backup image can only be restored onto the PS3 from which it came (though you can restore it to a new hard drive on that same PS3).
3. Your best option would be to use the
data transfer utility (should be under System Settings, assuming your firmware is new enough (late 2009, I believe) to have that utility; I think the two machines may also have to have the same firmware version), which is specifically for moving the hard drive contents from one PS3 to another.
4. The new PS3 would need to be activated under your PSN account in order to play any games (or video content, a
separate activation) you had bought on the PS Store. "Account Activation" (which also handles deactivation) should be under "Account Management," which appears on the XMB once you're logged into PSN. Since the limit going forward for number of systems on which you can play a purchased game is now 2 PS3s (still 5 PS3s for any games you bought before November 18th), you should make sure to deactivate your original PS3 from your account before taking it offline, so that it's not uselessly occupying one of your available activations. If you forget to do this, you can still do a "remotely deactivate all my systems" procedure at a Sony website whose address I've forgotten, though you can only do that once every 6 months.
5. As an alternative to using the data transfer utility, you could always just copy the game saves to an external USB drive and recopy them to the newly acquired PS3, along with re-downloading the games themselves once that PS3 is activated on your PSN account. Be aware, though, that certain games don't allow their saves to be copied. I seem to recall
Namco Museum Essentials being one such title. Also, video content can't be transferred this way, though I think it
would be possible to copy video content to a USB-connected PSP (one that's activated on your PSN account for video content) and then copy it from that PSP to the newly acquired PS3. I'm not certain on this last bit, though; the rules given in the Terms of Service for how you can move purchased video content don't address all the possibilities.
onmode-ky