I've got a Raspberry Pi with Wi-Pi and XBian installed. All works great until I try to look at high def 720p over wireless network. Is there a way to tweak the original settings to increase the network buffer? I have not yet tried to change gpu_mem.
Edit the advancedsettings.xml
Change the value to something bigger. It's in bytes.
Reference here http://wiki.xbmc.org/?title=advancedsettings.xml