good point, but by not sharing files you've downloaded that is just promoting leeching. So xolox's intention is a good one for xolox users and in turn gnutella.

As far as virus's, as you may or may not know xolox will automatically scan every file downloaded using the virus scanner of your choice. ( see the howto in faq of main page).

Additionally 1.4 if you choose to show a hash verification warning, will allow you to delete a corrupt file before sharing it.

The hash verifications are rather high on multi-source downloads likely because of certain clients on gnutella that add data to a file and although files that fail the expected hash value still work, it is now a new file as far as sha1 is concerned.