The ps3 wireless is 802.11g, which operates at roughly the same frequency as microwave ovens, and a lot of other stuff.
If you're just browsing from a PC, you might not even notice a momentary network glitch, but when you get dropped out of an on-line game session and lose a bucketful of XP, you will notice.
It's really easy to run an ethernet cable through the roof and down the inside of the wall. I have a slim model now, but i also had one of the launch PS3s until it yellow lighted on me.Ever since, I've not noticed any bandwidth problems. You could test by temporarily moving your PS3/tv into a room where you can hook it via ethernet.It would be a pain, but at least you'd know if it fixes the problem.Definitely no special skills or handyman experience required. Previously i was getting great speeds but now not so much.
Supposedly your house can support any number of these devices at 85Mbps. I would get abysmally low bandwidth when streaming internally or from the internet.
My solution was to move my base station into the entertainment center and connect the PS3 to it via ethernet.