My sound seems half off & half on, make sense???

Well looking at some of this questions from other newbies I feel totally at the bottom of the class.
I am a total novice & newbie. I was hopping along nicely on Windows, apart from the frequent viruses, worms & crashes ect, until one worm to many & my son who is a programmer downloaded Linux & said, you'll love it mum, and yes i do apart from a few teething problems, I wont go into them all now as one at a time is enough for me... I have or seem to have a problem with my sound, I have a Logitech Premium headset, which were gr8 on windows but on Linux, their not so good. I can here when I chat on Skype, no problems there, but try listening to any clips, as on utube or ecards & theirs not a sound, I have tested the sound on sound prefurences & all four test buttons give me sound, so where am i going wrong please? can someone help me? I just feel totaly lost with at the moment.

Hi,

Don't worry about being a "newbie" - we all start somewhere :)

Right... what version of Linux are you running?
("Linux" is just the core of the operating system, its the "Distro" name I need to know. It'll be something like "Ubuntu", "Kbuntu", "Redhat" or "Suse")

Kind Regards,
Johnathon