100% background on different post IE8

Hi,

I’m struggling with the following issue:
I’m making a site in WP with the following requirements:

– full page background
– different background for different posts
– has to work in IE8

The first I could solve with:

background-size:100%; in css
this works for all browsers except IE8 ??

for the second item I could use a css depending on the ID of the page:
like:
body.page-id-37{
background-image:url(‘/wp-content/uploads/2012/03/imagine-that-Background-project-management-medium.jpg’) !important;
background-size: 100%;
background-attachment:fixed !important;
}

works but the 100% size doesn’t work in IE8.

Is there any way to get all of this working in IE8.
Any kind of wp plugin / jquery that can do the trick?

I’ve searched quite a lot on this one, any help will be appreciated!
Thanks & best regards,

Koen