How to REALLY Remove unwanted software?

Running Kaspersky & HJT pointed out to me that some old (read: "unused" and "unwanted") programs were still in the system.

Running "Add/Remove Programs" said it removed them (or some of them) but when I look at c:\program files\ I find the directories and much of the contents still there...

I actually have a similar problem with Symantec's NAV and friends - I tried to update NAV about a year ago, and couldn't get it to update. Literally hours on phones and email exchanges with Symantec's (alleged) Technical (alleged) Support failed to get it updated. I even tried their program that supposedly removed all Symantec software from the system - it, of course, removed the only Symantec program I really wanted (PCAnywhere) but still didn't allow an update or even a fresh install of NAV... it isn't running (or apparently is not), so I finally gave up and just ignored it... but HJT shows several entries for Symantec. I think now I really would like to get totally rid of them, once and for all. I don't see a "Symantec" directory in \program files\ anymore, but HJT shows an O4 reference to them...

I understand this is not a S&D issue, nor (probably) a malware issue, but I am hoping that some of you experts can at least point me to the right place(s). Yes, google suggests some... thousands - no, tens of thousands - of them, in fact... but I am hoping that someone can - and will - take a couple of minutes and save me untold hours of fruitless dredging through toxic swamps of "information", and tell me where the "good stuff" can be found!

I don't want to abuse this resource, so if there's another forum you could recommend to take the issue to, I'll be happy to go away.

Thanks!