CGI.pm want the args to have a leading dash, then convert all dashes in the name to underscores. So, to fix your example (pardon my win32 :):

perl -MCGI -e "$q = new CGI ; print $q->Tr({-font_family => 'not-valid
+'})"
[download]

Gives

<tr font-family="not-valid" />
[download]

and to fix up the inital params:

use CGI;
$q = new CGI;

print $q->Tr({
    -align       => "CENTER",
    -valign      => "TOP",
    -bgcolor     => "blue",
    -font_color  => "yellow",
    -font_family => "verdana, arial, helvetica",
    -font_size   => "12"
});
[download]

gives

<tr valign="TOP" font-family="verdana, arial, helvetica" font-color="y
+ellow" align="CENTER" font-size="12" bgcolor="blue" />
[download]

--
"I don't intend for this to take on a political tone. I'm just here for the drugs." --Nancy Reagan