Best font family for accessibility? / site check request

Hi All

Have just been checking out the RNIB site but cant find any recommendations
as to the best font family to use.

Currently, I use this...
font-family: verdana, arial, helvetica, sans-serif;

Can I do any better than that?  It didn't look very good on Win IE 5.5.
Doesn't seem half bad on the Mac though.

Any advice?

Cheers

Carl

PS Any comments on my site would also be very welcomed (I still need to do a
little more with access keys - will probably follow UK government guidelines
since these seem the only ones out there.)

Site here...
http://www.impingtonswimmingclub.org.uk/index_css12.html

CSS here...
http://www.impingtonswimmingclub.org.uk/isc.css