[Lynne]

I guess you could reduce the width of the last column:
.threadbit .threadpostedin {max-width: 15%;}
(was 19.9%)

And the replies column:
.threadbit .threadstats {max-width: 10%}
(was 15%)

and then increase the threadinfo area:
.threadbit .threadinfo {width: 54%}
(was 45%)

You can see if those numbers work for you. You may need to make them specific to the search results page by adding something like div.searchresults in front of each of those.