Routers vs. PC's for routing - was list problems?

We've had some rather good success with PC based routers. Typical
setup was FreeBSD 4.x, 512mb, 20gb RAID-1, 3com Gigabit Ethernet card,
Fore Systems OC3 ATM card. All this, with zebra on top. It worked well for
a long time, although it turned out getting deprecated because of some
zebra issues (with ospfd. They (the problems) weren't confirmed by the
zebra community but thats the only thing we could narrow it down to.
ospfd would die periodically.) The line cards were bought off of eBay.
We did VLAN trunking through the 3com GBE card to a Catalyst 3548. Did any
rate limiting with DUMMYNET and ipfw pipes. Overall, the whole system
worked great for a few months without human interaction,
until the ospfd problems.

Feel free to contact me off list if you have any questions. I dont know
all of the exact hardware/software tweaking that were done; alot of them
were left default, but i'll try to help.