Hardware vs software firewall on FreeBSD

[ppi at amug.org]

I'm upgrading the hardware on my webserver.  It will run FreeBSD 4.9.

I need to decide whether to use a hardware firewall (Cisco) or use ipfw,
ipf, pf, etc.

The hardware firewall will increase my monthly server rental bill by
almost 30%.  So I'm wondering if the significant extra cost is worth it.

What kind of performance hit will result from using ipfw, ipf or pf?

I would like to avoid the extra expense of the hardware firewall.

Can anyone offer an opinion on this matter?  Any good reasons to use one
over the other?

Mark L.