out of the FREE Anti-Virus programs… i personally like “Avira” the most cause Avast i find to be horrible on resources! … AVG is decent.
the only catch with Avira is that every time it updates it’s virus definitions (basically 1 time per day) it has 1 pop up ad but it’s not a big deal and you can simply close it and that’s the end of it.
for simple mainstream p2p stuff… Frostwire (www.frostwire.com) (it’s free and open-source to) … but i typically dont use it much myself, maybe once in a great while i use it (mainly for finding a single song or something) … also i would not recommend downloading anything but music from p2p in general as it’s a quick way to get infected with a virus if you dont know what your doing etc.
for pretty much everything else i use USENET (i.e. newsgroups) but those cost money (im assuming your ISP dont offer good ones which most dont nowadays) but for the speed and ease of use etc it’s easily worth every cent of that 11 dollars a month through through astraweb ( http://www.news.astraweb.com/specials/kleverig-11.html ) but if you aint familiar with this it’s not super easy to use like Frostwire etc is but once you know how to use it… it’s far better than standard p2p crap… basically that newsgroup stuff carries files for 160days (i.e. 160 days data retention) before it’s removed from there server and it will MAX OUT your internet line in speed which torrents usually wont do… plus torrents typically tax your internet line since it makes many many connections… plus newsgroups offer SSL (encrypted transfers, meaning no one can see what your downloading) to which is a nice benefit… to use newsgroups you need a newsgroup client (i recommend Alt.Binz , http://www.altbinz.net/ , which is free) and use a website like ‘binsearch.info’ or ‘newzleech.com’ to find what you need etc etc… i aint going to go into details on how to use it right now.
if you want something easy to use ‘torrent’ (which is better than crap like Frostwire in general, u need to use sites like isohunt.com or piratebay.org etc to find what you need) are probably most mainstream stuff and free… for a torrent client i recommend ‘utorrent’ it’s free and lite on resources.