i know theres probably better forums to find this out and i have looked around google but lots of people asking with no answers. never know someone might know this problem here.

So i removed windows completely and installed 'Ubuntu 10.04' now everything works fine apart from high quality video. for instance 720p/1080p mkv's and hd video on youtube are all jerky and getting artefacts on the hd rips ive downloaded. also streams such as lvlup are jerky.
this is on my netbook with the specs being Atom 270/3gb ddr3 ram/ION GPU. 1080p, streams and other high quality video all worked fine in windows xp and windows 7, just having problems since switching to Ubuntu.
i did read in one place that the video decoder with ubuntu is quite slow so this could be a reason, they gave CoreAVC as a solution but wouldnt this only work for my downloaded videos i play in a player and not solve youtube and lvlup etc?