If your Ps3 is connecting to the Internet via a Modem/router then just plug the Ps3 in as a network item.You can make an automatic address setting so no real work required.I would suggest you do this 1st of all with a short Network lead so Ps3 & Display,are as close as possible this saves running backwards & forwards between rooms.Once you have it networked you can then decide where you want it set up and work out how to put your cable in.I did mine via Loft and wall Ethernet plug ins(Female),but if that is impossible you can get special Electrical plugs that carry the program streaming via your mains electric system.(3 leads required one at each end Modem & Ps3and from PC to modem and two of the special the
plugs)This is the easiest method but could be a little more expensive (if you intend to have a larger network eventually) but no installation work is required other than plugging in the special Power plugs which have a place to plug the male Ethernet cable into, You would require 2 Ethernet patch leads one for each end (Modem & Ps3) I was advised at one stage that the mains plugs required to be on the same mains circuit,IE the same fuse should control both of the power points being used but suggest you check this out further.
Once you have obtained a good connection you will never use wireless again,
There are numerous instructions on the web if you get stuck.A cross over cable is only required if you do not have a router and no network
I transferred to a wired Ethernet system and have installed them for friends, no one who has changed over,ever goes back to wireless,we all stream 1080 faultlessly