Why not just use the free ones, they are less resource intensive, no mem leaks and no monopoly
Sygate, Kerio and many other firewall engines are exceptionally good, so why pay for them??
AVG is a very good AV tool, and again the resources required are minimul ( I can't spell
A pair of spybot tools are always a good idea, adaware SE and spybot have never let me down (touch wood).
But if you really want to relieve the stress off of your personal machine, there are a number of very good stand alone devices available on eBay that would suit you perfectly. Even more reliable and cheaper is to get some old box and whack Smoothwall onto it, cost = the time to download, has built in failsafe and deny all policy, VPN buil in too, and can run on anything that can boot, DX66 would even manage it.
Good luck, and all the best