Typically, about as large as a stack of three CDs in jewel cases.
Yes a USB is an External HDD, but it just depends on the size....
A DVD hdd recorder can be purchased from Amazon for approximately $200.00. This does not include shipping but this is the average price on their website.
Picture quality, comfort, battery life, ram size, hdd size, durability, size.
The average price range of a good quality HDD player is around $300-$500. These prices may vary, though, if the HDD player is being bought new or used.
PS3s do not even have a memory card they have a laptop size hdd
Yes you can upgrade the HDD on a PS3. Not sure whether 360HDD is available in standard notebook size, but 320 HDD is and I some larger more expensive sizes are said to be available.
Yes. You can buy an enclosure at many stores that sell hard drives. Install the laptop HDD in the enclosure (be sure to get the correct size). Then it will connect to a desktop USB port.
HDD RPM speed ?
The amount of RAM in a system has no bearing on the size hard drive you can use.
hdd
Standard notebook size harddrive. See related link to PS3 support for detailed information
HDD stande for High Def drive