thanks for the replies / information, all very good feedback on this question. I have been using smoothwall for quite some time now back to 2.0 actually and with a little massaging of dan's guardian and some other homebrew mods it has worked exceptionally well on the most antiquated hardware.
I actually have a smoothwall 2.0 running on a Pentium 133 with 128MB ram and a 5Gb WD drive, the thing is a dinosaur (but smooth loves it). humms right along, never a complaint about the internet being slow or anything.
Right now at home I am using my main desktop and the rc.firewall generated from AlienBob's wonderful site with some minor modifications, I also have Dan's installed, snort and clamav, SElinux with a few custom scripts that parse logs and send me email based on certain criteria it might detect in the logs.
Online gaming through it is awesome, no issues, but gaming through the older smoothie box is questionable with 3 clients...i guess depends on solution and user base as always...
Seems like I have a little more functionality with the Slack build (plus 64 bit support)
In the end i just installed the 32bit smoothie and the mods and moved on...works quit well, and since this is only a health care facility there are only like 14 websites allowed out through it, so once again user base and logic win out
Thanks again for the replies and thoughts
Rasta420