Which masks protect from the H5N1 bird flu virus?

With the bird flu virus spreading across Europe and approaching the US, I thought I’d ask the obvious $64,000 question: Which face masks provide a reasonably high degree of protection against the H5N1 bird flu virus?

A number of websites sell the N95 mask. Another website makes this claim:

“… There is only one filter mask in the world marketplace that will block and kill H5N1, and that mask isn’t an N95. [Our] eBook details exactly where the filter mask can be bought and why it’s important.”

Yet another website touts the N-100 respirator mask.

Without getting into GD or IMHO, which mask is appropriate, without going so far as wearing the bio-hazard suit?