This is a total Pain in the butt with win7 (that is until you accomplish it) I have two laptops, two routers, 1 desktop w/NIC and popcorn hur a110, xb360, wifi wii. Im telling you I had a heck of a time not robbing peter to pay paul to get a connection. The whole time I didnt realize that my system had to be JB first.
you need a crossover cable if you want to plug it directly to your pc, that is what i use to stream movie off my pc to ps3. First you need a computer with 2 ethernet port, or 1 ethernet port with wireless internet. then go to control panel->network connection-> you should see 2 local area network if you are using 2 ethernet port, and 1 wireless and 1 area network if you are using it with wireless->highlight both of them->right click->bridge. and the cossover cable one end looks like a normal ethernet color plug that one to the computer, and the odd color side go to your ps3.
Best option here is to wire everything into a router. Just install one cable (in the roof or along the floor under carpet etc) from where the router is to where your ps3 and PC sit. Then grab yourself a cheap 4 or 8 port switch to plug into the cable from your router and then wire in the PC and PS3 to the switch.
figured it out what I had to do was of course use a crossover cable then I had to right click on my wifi adapter then click properties then click advance then click share and then goto ps3 and make sure you pull an ip and there you go I am getting transfer speeds of 30Mbps!
actually, all you have to do is bridge your wifi and ethernet connections, then on the ps3 you setup a wired network like you would usually do it. there you go, your ps3 is bridged to your computer via crossover cable. 20-40MB/s