Say i am online but not using the internet (i.e. surfing the web, downloading, using a chat, etc) but browsing through files on the comp or just listening to music, will ISP or anyone know what i am doing??

So what im saying is, as long as your online whatever you do on the computer is noticeable, is that true???

I know this is stupid but i was always curious as to how these two "dimensions" are separated.

Your computer is noticeable - I could ping you or probe you.
But all that is doing is saying "I am here" nothing else.
And if you have your firewalls well set you won't even get that.

So, if you have ADSL and are always on but all you are doing is looking at images then, no, no-one will know what you are doing.

That said!

A lot of people do not have their systems well protected so it could be very easy for someone to have a program installed that could let them see what you are doing and what is on your system.

If you are doing anything, I meant anything, that could get you sent down and your name on some sort of register - unplug your PC from the net or turn your modem off.

I don't care if people think I'm too paranoid - it takes 10 sec to unplug your system and 10 sec to plug it back in again - sure beats 2+ years sitting next to Bubba who thinks you have pretty eyes.

Also, keep everything you don't want anyone else to see on an encrypted disk. Again, better safe than sorry.

for a VERY SHORT time the beta " Google Desk top search " tool bar was ( by mistake ) indexing the users hard drive and allowing EVERYONE to download/copy YOUR FILES .The ones on your drive .This lasted for about a week or two until it was noticed ,then it was fixed very fast .

Things happen

this is called " stealth blocking " where NO response is given to a port ping .The regular response is for the OS to reply with a " this port is closed" call

I do have a firewall but dont know how to stealth block, how do you do it?

Your modem should have a built in firewall which will block most things

a good software firewall (Comodo is free for example) will add an extra layer and prevent unauthorized out goings

for further information try this first
https://www.grc.com/x/ne.dll?bh0bkyd2

then if you need
http://www.grc.com/su-firewalls.htm

The information is a tad out of date with some things but the basic information is sound.

You could then do a search for more information relevant to your system

if you use Norton or Mcaffe FULL packages then that type of blocking is auto on by default

While this topic is still active, I want to get some useful insight, too.
What is a great firewall and antivirus program to buy? If I'm willing to spend $100+ on those types of software, what would you folks recommend?

Well i have Nod32 and Zone Alarm and have no problems then again i would not know if i had one i guess with my limited computer geek knowledge but if you google them they are rated highly.

just shoot me for saying this but the firewall in vista is not bad ( xp only blocks incoming ) vista will block incoming and outgoing( If some malware gets on then it can not call home with your "tax cut, MS excel, passwords,... files)
For AV it is a toss-up do some reading on " pc world" or " pc mag" then use google.
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but to be "secure " then run Linux with " iptables" and " SELinux" kernel , turn off unused services and turn off unneeded ports.

If you want my advise Dont go anywhere near anything that says norton on it !!

far too big and resourse hungry ( makes your PC really slow ! )

AVG ( hXXp://free.avg.com/download-avg-anti-virus-free-edition )

will give very good protection for free !!

Peace

Anti-virus
AVG free version is fine for most people.
Reliable and accurate.

Firewall
Comodo - free but does require some technical experience. What I like about it is it can also monitor disk and file access, and incoming and outgoing connections.