Some people do get asked by the PS3 for the firmware when installing a new HDD. No idea why though. I think part of the Store may be kept on the HDD, but AFAIK the firmware itself is kept on flash memory.
Regarding firmware though, you can put it on a USB flash drive, external HDD, etc., & install it to the PS3 from there (instead of letting the PS3 download it, or for "just in case" the PS3 wants it when fitting a new HDD). It must be stored in "\PS3\UPDATE\" to be found by the PS3. It's 153MB in size, & can be found at http://uk.playstation.com/ps3/support/system-software/
. I find it easier doing updates that way than letting the PS3 download it itself.
If changing HDDs, you can perform a backup using the XMB, to backup your game saves, game data, etc. to an external HDD. Or you can just copy your game saves to a flash drive / external HDD manually, & then re-download any game updates & DLC after the new drive has been fitted.
Fitting a new HDD on the PS3 is easy. Just make sure you get the right size SATA drive (2.5").
---------- Post added at 15:59 ---------- Previous post was at 15:58 ----------
Originally Posted by zing
as it should not in all fairness you are hardly doing anything invasive. Shame M$ are not so cool about it
The 250GB drive I fitted to my PS3 was far cheaper than the cost of MS' 120GB HDD for the 360
Heh, and I could probably get a 500GB drive now for what I paid for the 250GB drive.