You have to have a media server "serving" the media to your network, so donwload something like tvesity or twonky (or you could use windows media player 11). From here, you tell the server to allow the sharing of media accross the network. From WMP you go to sharing, then allow the unknown device to see your media(this is actually your ps3). Then the server will appear on the xmb under the appropriate sections, ie video, pics and music.
If you need any more specific help just give a shout
if you download ps media tunell for your laptop you can access your laptop from your ps3 web broswer and download music films etc
Nice, will give it a go cheers!
OP, we told you how to do this yesterday dude.