No other single product class seems to cause as much angst to average users, in their installation and day-to-day use, as Firewalls.
For such users, Sunbelt-Kerio Personal Firewall is my top recommendation, as it seems to cause the fewest problems yet manages reasonable protection as well.
Kerio dropped the product in late 2005 but, thankfully, Sunbelt Software, the makers of the excellent CounterSpy anti-spyware scanner, picked it up and will continue making it available. Note that the free and paid versions of Sunbelt Kerio are the same. If you don't buy the product, some advanced features are automatically turned off after 30 days. The product will also nag you every time you start it. For some, this is a small price to pay for a great free firewall. For others, it's a real turnoff.
If performance rather than ease of use is your criterion, then the Comodo firewall is the top contender. The firewall itself is very robust, and the just-released version 3 includes a well designed intrusion detection system and Vista compatibility as well. Comodo also supports internet connection sharing, whereas the free versions of Kerio and ZoneAlarm do not. On the minus side, the IDS is initially rather talkative, and this may unnecessarily alarm inexperienced users. There have also been reports that the new version 3 has some new version bugs, so it may be better to wait a couple of months until the new version has stabilized before you install it. Additionally, Comodo has been known to conflict with some other security products. However, for the technically initiated who can cope with these annoyances, this is an outstanding free product and an easy first choice. Make sure, though, that you install it in the "Advanced" mode, because the "Basic" installation has the HIPS and outbound protection disabled.
A recent contender is the free version of Online Armor Personal Firewall V2, which has been getting praise for its outstanding leak-test performance and ease of use. The full commercial version a while back and was impressed, Certainly the feedback from users has been very positive.
Also technically impressive is the Jetico Firewall. It rates highest on the leak tests of all firewalls, but It it awkward to use. It may, however, be just your cup of tea.
Another tricky product is NetVeda Safety.Net firewall. However, it's performance is quite outstanding and it offers application control and content filtering as well. This highly capable product deserves to be better known, and experienced users should definitely put it on their short list.
I don't recommend the free version of the ZoneAlarm firewall. First, it is a very basic product compared to the commercial ZoneAlarm Pro version. The leak-test performance of the latest free version is extremely poor, whereas the Pro version is excellent. The download also includes the large commercial ZoneAlarm suite, so be careful not to install it. On the plus side, ZA free does have the advantage of working with Vista.
Sunbelt-Kerio Personal Firewall
Website: http://www.sunbelt-software.com/Home-Home-Office/Sunbelt-Personal-Firewall/
Download link: http://www.sunbelt-software.com/Home-Home-Office/Sunbelt-Personal-Firewall/
Author: Sunbelt Software
Current version: 4.5.916
Version date: April 26, 2007
Download file size: 6.27MB
License: Freeware
Operating systems supported: Windows 2000/XP
Additional software required: None
64 Bit capable: No
Portable version available: No
Non-English languages supported: Yes
Other relevant information:
Comodo firewall
Website: http://www.personalfirewall.comodo.com/
Download link: http://www.personalfirewall.comodo.com/download_firewall.html
Author: Comodo Group
Current version: 3.0.15.277
Version date: January 11, 2008
Download file size: 9.08MB
License: Freeware
Operating systems supported: Windows Xp/Vista
Additional software required: No
64 Bit capable: Yes
Portable version available: No
Non-English languages supported: Yes
Other relevant information: Version 2.4 is available for Windows 2000
Online Armor Personal Firewall V2
Website: http://www.tallemu.com/product_overview.html
Download link: http://www.tallemu.com/downloads.html
Author: Tall Emu Pty Ltd
Current version: 2.1.0.31
Version date: November 16, 2007
Download file size: 14.9MB
License: Freeware
Operating systems supported: Windows NT/2000/XP
Additional software required: None
64 Bit capable: No
Portable version available: No
Non-English languages supported: No
Other relevant information: Free version doesn't include Mail Shield (spam filter) or automatic updates
Jetico Firewall
Website: http://www.jetico.com/jpfirewall.htm
Download link: http://www.jetico.com/jpfirewall.htm
Author: Jetico, Inc.
Current version: 1.0.1.61
Version date: July 19, 2005
Download file size: 2.67MB
License: Freeware
Operating systems supported: Windows 98/Me/NT/2000/XP
Additional software required: None
64 Bit capable: Yes
Portable version available: No
Non-English languages supported: Yes
Other relevant information:
NetVeda Safety.Net firewall
Website: http://www.netveda.com/consumer/safetynet.htm
Download link: http://www.netveda.com/downloads/index.htm
Author: NetVeda
Current version: 3.8.1
Version date: October 7th, 2007
Download file size: 4.31MB
License: Freeware
Operating systems supported: Windows 95/98/Me/2000/XP
Additional software required: None
64 Bit capable: No
Portable version available: No
Non-English languages supported: No
Other relevant information:
ZoneAlarm free firewall
Website: http://www.zonealarm.com/store/content/catalog/products/sku_list_za.jsp
Download link: http://www.zonealarm.com/store/content/company/products/znalm/freeDownload.jsp
Author: Check Point Software
Current version: 7.0.462.000
Version date: December 14, 2007
Download file size: 205KB
License: Freeware
Operating systems supported: Windows 2000/XP/Vista
Additional software required: None
64 Bit capable: No
Portable version available: No
Non-English languages supported: Yes
Other relevant information: