Why is it so easy to install WebWatcher Spyware on your computer even if you have protection?

If someone has access to your computer they can easily install a spyware program like WebWatcher, NetNanny and others, that have keyloggers, email viewing and screen shots and send your private info to them, even when you have a firewall, antivirus and antispyware programs that are supposed to protect you? They don't show up in the usual places so you can't see them...

How can you find out if you have one of these snooping programs lurking right now and get rid of them?

Serious knowledgeable answers only please!

Why is it so easy to install WebWatcher Spyware on your computer even if you have protection?free anti virus

That's because your using inferior software to protect your computer. Now the best software you should get is Spysweeper with Anti-virus, this software is too good and gets better everyday. This is ELITE software. It blocks over 173,000 threats. No other software can compete with that or come close for that matter. It catches everything and has active shields and programs can not install on your computer without premission if you so desire. I've used them all and it is 2nd to none. Norton Systemworks is very good. That's the only good software from Norton. I wouldn't recommend Norton Internet security, its not that great. Norton is not a system hog either and it's the 2nd best.

I recommend getting ZoneAlarm firewall, it is the best firewall out there.

Don't waste your time with AVG, spybot, ad aware, CA, spyhunter, superantispyware, windows defender or anything of the sort. Stay away from anything that is FREE when it comes to spyware and antivirus. There is a reason why they free. They are NOT good.