Lots of questions here. I've never noticed a difference in a 160 & 320 access time. If the hard drive has been defragmented on the volume optimized it really doesn't matter. Think of it as a book shelf, if the catalog knows where the system information is and it's all in order, there's no problem finding it no matter how large the library or hard drive. No brackets needed that aren't already there. Replace the DVD when it fails or get an external. Don't fool with extra USB ports. If needed get a USB hub. You have the maximum RAM for your machine. I'll let someone else help with the RCA cabling. What upgrades are you looking for? Will Amazon give you the help you're getting here? Go here for parts: http://www.ifixit.com/Parts-Store