RCTfansMal818 - PS3 may have 4x more space but XBox will have the HD AND as I said above, PS3 will be almost 4x slower when reading from the DVD so its pretty pointless to have all that room when you cant read it to the processor fast enough.
Its like having a brand new computer with a 12x CDROM. You wont get nearly the potential out of it.
Princess G - XBox 360 is backwards compatible as well