Image replacement techniques fail with IE accessiblity settings

I've seen a number of sites recently use variants of image replacement 
techniques to make graphical headings etc. accessible.

There are a number of methods that appear to have different successes with 
screen readers etc.

They all appear to suffer however if CSS is on and images are off (which 
may be pretty rare), or and this is not that rare for people with visual 
impairments, they use the IE accessibility settings - specifically: tools - 
Internet options - accessibility - ignore colours specified on web pages.

I have recently user tested with 2 visually impaired people who use 
different screen magnification software combined with the microsoft IE 
accessibility settings - they missed out on all sorts of information - 
headings, menus etc.

I can think of a way round this - but its a bit of a hack: put a link that 
only appears when colours are ignored and the link affects (or disables) 
the stylesheet to return the lost menus.

I generally resist tailoring content for specific browsers or technologies 
(standards and all that) but this is a real practical issue that will 
affect a host of people.

Any other suggestions or experiences with this?

Cheers

Jon

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