PeerBlock lets you control who your computer "talks to" on the Internet. By selecting appropriate lists of "known bad" computers, you can block communication with advertising or spyware oriented servers, computers monitoring your p2p activities, computers which have been "hacked", even entire countries! They can't get in to your computer, and your computer won't try to send them anything either.
PeerGuardian 2 users should check out PeerBlock, which just released version 1.0. It is a continuation from where PeerGuardian 2 development left off, with many bug fixes and support for Windows Vista and Windows 7.

PeerBlock runs great on Windows 2000, XP, Vista, and 7 (plus server variants), both 32- and 64-bit versions.

Installation
No need to uninstall a previous version of PeerBlock before installing PeerBlock 1.0 - you just need to exit any currently-running version, then download and run the installer. (Or unzip the .zip-file into the same directory you'd had PeerBlock unzipped into.) Note that this version of the installer will not detect whether a previous version of PeerBlock is running however...

Many, many changes are present in this release versus the most recent Stable Release, PeerBlock 0.9.2 (r86). Here are the highlights, you can check out the Changes page for more details.
1. Signed Driver - We now have a signed driver! If you're using a 64-bit version of Windows Vista or 7, you will no longer need to test-sign the driver, or hit F8 during boot, or anything else. It should all just work!
2. iBlocklist Lists - We've updated our standard list URLs to point at iblocklist.com lists instead of the original peerguardian.sourceforge.net ones. They are faster, and are much more reliable - no more "Error contacting URL" messages! We will also upgrade your pre-existing lists from sourceforge.net hosted ones to iblocklist.com ones. Also note that the "Gov" list has been removed, since its contents were merged with the "P2P" list long ago.
3. Installer Rewrite - Our newest Dev Team member, XhmikosR, has pretty much completely rewritten the installer from scratch. Most importantly, it should actually work now, even during uninstall! (Not that you'll ever want to uninstall PeerBlock, of course, but just in case...)
4. Updated List Manager - Reworked this window a bit, to make it easier to get back to the lists originally presented to you in the Startup Wizard.
5. Allowed Connections Displayed - By default, the "Show allowed connections" option will be disabled. (This is due to performance reasons, as the tool will consume considerably more CPU if displaying of allowed connections is enabled.) We are still logging the first 9 allowed packets though, so that you know that we're actually working!
6. Save Settings - We've added a "Save" button to the settings panel, so that you can be sure your settings updates have been saved.
7. List Verification - After downloading an updated list, we'll now make sure that the file contains at least one ip-address range before we'll overwrite your old list. This way you will be protected against your lists being corrupted while downloading them.

The license of this software is Freeware, you can free download and free use this firewall software.