Limewire 5.1.1
 

After doing a search it would really be nice to sort the files for size from highest to lowest. Currently you can only sort from lowest to highest and if you do this all you get is the junk stuff at the top and have to scroll way down for any real file size.

I can sort by size either way. When you click on Size, the arrow pointing up sorts with smallest file at the top of the page. Click on Size again & the arrow points down - and sorts by size with the largest file at the top.
:)

Yes, double-clicking the column heading always arranges largest at top, smallest at bottom. Same principle applies to all column headings. :) That's when the arrow is pointing downward as Birdy suggested.