If you're after the truly authentic Hammond sound,
any soundfont or
sample is likely to disapoint. Unless you've got a Leslie speaker on
your Linux box, maybe? : )
There is another soundfont on that page marked OB-3, plus a Farfisa
soundfont. There is also a second page of soundfonts if you click at
the end of that page. I don't think they are bad for free-as-in-beer
samples.
BTW - I am not an organ player, but I have a couple of really great
GigaSampler GIG files of B3's. They are very convincing, and were only about
$15 each from Sonic Implants I think.
Obviously this doesn't do you any immediate good under Linux, as far as I
know, but I thought I'd chime in in case you have some tools I don't know
about.
Cheers,
Mark