Thanks to LBOT, I replaced my old Linux internet firewall (which was a Pentium 100MHz) with something not much larger than a paperback novel, I'd have to say I'm pretty happy.
What I like about it is:
\- It's fanless
\- It's diskless (It has a solid state disk which has an IDE interface)
\- So it's incredibly quiet
\- It's based around mostly RedHat, but with a lot of binaries replaced with busybox versions (for compactness)
\- It has 3 fast ethernet ports, so makes an ideal 3-legged firewall/router
\- It has low power consumption (works off of a 12V DC power supply)
I mainly use it for:
\- Iptables
\- OpenVPN
\- Squid
\- DHCPD
\- BIND
\- Asterisk
\- Syslog
\- NTPD
\- DDNS
What it's missing is mail (store & forward), mainly because of lack of disk space. LBOT is designed to run mostly out of ram disk, to avoid repeated writes to the flash memory.
Overall, I'm very happy with it. It just sits in the computer cupboard filtering packets.