FYI: I’m currently running Kerio Personal Firewall, McAfee VS (vs.5.21), Avast Home 4, Diamond Registry Prot., and System Safe Gold. Yes concurrently and with no apparent problems.
P3 Dell 1gig, 384MB PC800 RDRAM, W98se (all patches), OX6, DX9, Turtle Beach Santa Cruz sound card, Nvidia 64MB vid. card and using both OX and Eudora for mail along with OX and Xnew for newsgroups.
Yeah I know the security is overkill but I have the stuff so I use it.
Your milage may differ.