Thrednedul
The ultimate free software list - compiled by PPRUNers has to be the place to go - its all be said there.
Also on Firewalls - with the dangers today you must find a solution to be somewhat safe. At the office we are moving to personal firewalls on all 16'000 PC's as the problems have become too great otherwise, in spite of central firewalls at the network entry points!!!. Went live a few weeks ago & wors almost without problems (under 1% of users had something - not bad for an automatic system download).