I am a home software tech.
I had previously been a happy user of Sygate 5.5.2637 free firewall. It started playing havoc with auto-updates, on my new XP 64bit computer. I decided to search for a compatible free firewall (Acronis 9.0 total system backup/restore, made this much easier...).

I tested Sunbelt Kerio free trial, on my new DELL XPS400, 3.2GHz Pentium D, 2000mb memory, Raptor 10,000 rpm single sata Hard Drive (WOW!- FAAAST!).
Pros- It passed ALL of the 7 advanced security tests 100%, that I threw at it. Default settings.
Cons-
1. Slowed my 8000Kbps cable internet download, to 900Kbps (testmy...)
2. Slowed restart/shutdown by 2 minutes!
3. Slowed my Symantec "total system" performance test, from 1350 to 450!
Uninstall, was VERY tricky!- Safe mode...

I then tried the Comodo free firewall- HORRIBLE interface, and wouldn't work in run-msconfig...! BAD!

I then found a free one I REALLY LIKE!-
Antitum, Outpost Firewall Free v1.0.1817. Default settings.
Pros- Passed all 7 security tests, and performance numbers returned to normal (same numbers as Sygate 5.5.2637 free  )), and allowed all auto-updates...
Cons- None with the basic version, but the Update version drove me NUTS, with "redundant" pop-up warnings.
I reinstalled basic, and "disabled" auto-update!
2. Then defragment your hard drive- I HIGHLY recommend Diskeeper PRO (40% faster!)>!

Welcome, scottls, and thanks for the info!