As well as whatever firewall and av you choose I would highly recommend the following.
AdAware - get it here
http://www.download.com/Ad-Aware-SE-Per ... ag=lst-0-1
Spyware Blaster - get it here
http://www.download.com/SpywareBlaster/ ... ag=lst-0-1
SpyBot Search and Destrot - get it here
http://www.download.com/Spybot-Search-D ... ag=lst-0-1
You shouldnt need any other spyware and malware solutions if you have these 3 products installed.
AdAware picks up your ad trackers and malicious cookies etc. Picks up somethings Spybot doesnt.
Spybot does some of the same things as Adaware but it picks up things adaware cant such as rogue diallers and stuff like that.
Spyware Blaster prevents most spyware from ever being able to be placed on your pc in the first place minimising the number of bots that will need to be removed by the above 2 progs.
So AV, FW and the 3 above should make for a secure PC!!
Hardware firewalls are always most effective but not always practical for most.
Wouldnt say an old PC is the greatest option for Kaspersky but that a p2-400 is the minimum you should use, if you want speed then obviously use a faster rig the point is that whatever you use should only have kaspersky on it. Then ALL (MOST) of that systems resources can be devoted to Kaspersky. As there wont be any conflicts in cpu requests K should and normally does run smoother and quicker. And you could still use wireless and adsl, jus make your devoted rig a fast one.[/url]