can you install a 7200 rpm 500 GB HDD on a playstation 3?

Yes you can but make sure it's PS3 compatible. It will also be very hard and you will lose all previous game data.

what data once i check that the ps3 is running then i'll change the HDD but also i'll keep the old one just in case. and plus its a laptop HDD that uses ATA SERIAL connections

No you cannot. The hard drives have to have the special PS3 operating system (Like windows or OS X) pre installed on them.

no you can sony says the macine has the OS on a different data base like theres a second HDD look at youtube and read the info on the ps3 at WWW.Playstation.COM

i think the HDD is only for game data and music and vids. the OS is already pre installed the the machine second DATA BASE

Oh, whoops I thought you were talking about a 360 for some reason. Sorry. But, what kind of hard drive is it and how big is it? Also, is English your first language?

The HDD must be 2.5 Inch and formatted to FAT 32. Doesnt matter how much GB the HDD has.
NO OS must be preinstalled.

Didn't IGN do a video on installing a 500GB into a PS3?

why would u need more than ps3s current memory?

why not?