Slow downloads and dodgy PS3 connections? Try this... Firstly let's start with a bit of wireless networking 101. Try getting a direct 'line of sight' between your wireless router and your PS3. Pull them out both out from alcoves and behind dense furniture and try to minimise the number of obstacles between both boxes. (Nothing degrades your Wi-Fi signal like a nice stone fireplace....)
Next, stand your PS3 on its on end. The PS3's antenna is located in the right hand side so standing it up on its left-edge gives it a bigger spread. Ideally put your router up on a high shelf.
Finally -and this is the clever bit - take a Coke can (other soft drinks are available)and cut the top off. Cut down the sides of the cup-like can and fan out the divisions slightly so it looks like a weird metal flower. Now make a hole in the bottom and place your new 'high-gain antenna' over your router's stubby aerial so it pokes through. Now point it at your PS3. Sounds mad, looks awful, but you could see a 10% boost in signal strength.