Step 1: Internet
The other program i would like to mention is utorrent. **NOTE: I am not endorsing internet piracy. Torrents, as with all peer-to-peer transfers, have legitimat uses, many things are in public domain, or are open-source**. that being said, utorrent is the lightest torrent software out there (weighing in at ~200 kilobytes). While I do not have any experience with other torrent programs, utorrent has treated me well. the great advantage to using torrents over other peer-to-peer transfers is that you are far less likely to pick up a virus, especially if you screen your transfers well.
The third is Sygate Personal Firewall. It is far better than the crappy windows firewall, which i disabled after this was installed. this software will ask you about which software you want to access your network. Every time something attempts to access the network, sygate will give you a nice little popup asking whether this software should be allowed through, at which point you can press yes or no, with the optional check to remember the answer for that software. it will also perform checks when software changes, i.e. when you update, or a program is mutated into a virulent form. It will also allow you to turn access fully on or fully off, fully open network is necessary for windows file sharing.