i would have to see your entire .css to help with the alignment..... but this is a little advice fwiw.... I use only margin and padding for alignment. I like using a page container as well.... I do it like this:
Body
{margin-left: 20%;
margin-right-20%;}
#Main-Container
{margin-left: 10%;
margin-right: 10%;}
and I never use absolute functions unless for a specific purpose. Also, I recommend using known sizes as opposed to percentages or em's.....so pt's and px are my rule of thumb.
as far as ie and media player, that could be a thousand things. You might want to load up a gallery like g2 and integrate it to the page/blog. it makes those things easier to load and for users to interact with regardless of users available plug-ins..their inherit flash player is a good thing.
check me out at here for an idea of what I am talking about....