Wallpaper & Mp3 Playback Issues

Hi folks,
got myself an aspire one, been personalising it with the advanced mode, wondering if there's a way to save the desktop background image so that it comes up everytime i restart my machine - i've got rid of the limpus menu and have reverted to the default linux desktop with icons. i have now changed the wallpaper to an image stored on the hard drive ( i have the 120GB aspire) but the next time i fire it up its reverted back to the plain blue default wallpaper. i've also done the 'edit list' and left it as the only one in there but still no joy.

I was also wondering if anyone's had problems with any other application other than the just plain shoddy 'media master' regarding mp3 playback, so far i've got a variety of error messages telling me i'm lacking codecs and plugins. I've installed all the plugins and codecs i could find in the package manager, but a) am unsure how to install a plugin any other way and b) cannot locate the synapse package manager everyone keeps talking about. So far Kaffeine, Gxine, Amarok and Audacious have all refused to play mp3s.
Banshee fails to install from the package manager.

I am new to linux so if anyone who knows the solution to these problems would be willing to simplify instructions as much as possible i would be eternally greatful.

the aspire one is such an amazing machine, just makes me wonder what use 120gb of hard drive space is when its such a ball-ache to install the simplist thing! :lol:

thanks in advance
d c :geek: