[Sisom]

Thanks for your help, I've taken a different tact:

I removed the 'position: absolute' property, from main.css, line 311:
#footer {
width: 100%;
/* position: absolute !important; */
bottom: 0;
overflow: hidden;
float: left;
}

then I removed the 'padding-bottom: 50px' property from altskin.css, line 57 (this is something that I added while customising the site):
#content-container {
/* padding-bottom: 50px; */
margin-top: 150px;
}

then I removed the 'padding-bottom: 39px' property from main.css, line 266 (this was the way it was with the original installation):
#content-container {
clear: both;
float: left;
overflow: hidden;
position: relative;
width: 100%;
/* padding-bottom: 39px; */
margin-top: 140px;
}

and now it's almost okay in IE8 (I just need to move the top line down by 5px - I am going to try floating this div, as it hasn't been floated in the original CSS (quelle surprise).