Chapter 1 : Bootup
Chapter 2 : Services
Chapter 3 : Drivers
Chapter 4 : Video Card and DirectX
Chapter 5 : Antivirus and Spyware
ANTIVIRUS
One of the most important things you need to run your computer properly is antivirus software. The three most popular are Norton, McAfee, and AVG. AVG is free which you can download from here
http://free.grisoft.com/freeweb.php/doc/2/
I recommend having two antivirus programs since each will catch problems the other will not. I recommend getting Norton Systemworks because not only do you get Norton Antivirus, but you get Norton Utilities and other goodies.
http://www.symantec.com/sabu/sysworks/basic/
Part of Utilities is Norton Windoctor which you should run at least weekly. This is an excellent program which will detect and fix numerous errors. You can usually pick up Norton Systemworks pretty cheaply especially if you pick up a previous years model, such as Norton Systemworks 2004. All you have to do is use live update to keep your virus definitions current.
Running virus scans should be a weekly or at the latest bi-weekly events. If you allow other people access to your computer, then I would suggest having virus scan running in the background all the time. This is because you do not know what other people will be doing on your computer and what websites they visit, or emails they receive.
I personally do not have virus scan running at all, because what virus scan does, is scan every file that you are using or attempting to use. This will slow down your computer and if your computer is not too fast to begin with, you will notice a performance drop. And if you are playing any games, you should definitely not have any Anti-virus program running. (See the games section for gaming advice)
If you choose not to have antivirus running all the time, then make sure you right click and scan with Norton Antivirus on anything you download from the internet of email.
SPYWARE
Spyware is one of the most hazardous things you can have on your computer. Your browser can be hijacked, and you can get endless popups.
There are a few programs which you need. Some are free, and some are shareware which you will have to pay for after awhile. This is not completely necessary since there are free software available, but if you would like to pay for a program I recommend here, then that is your choice. The paid programs usually have some protection running in the background to prevent spyware from getting onto your computer in the first place. But this eats up memory and affects performance. So you have to decide if you want it running depending on your system. (ie how much ram you have, CPU speed, etc)
The free ones are
Ad-aware
Spybot Search and Destroy
http://www.safer-networking.org/en/home/index.html
HiJackThis
SpywareBlaster
http://www.javacoolsoftware.com
Shareware ones are
Spy Sweeper
Giant Anti-Spyware
PestPatrol
http://www.pestpatrol.com/Products/PestPatrolHE/
SpywareBlaster is a program designed to prevent spyware from getting onto your computer in the first place, and will not be running in the background to eat up your system resources. I recommend getting all the free ones, plus any other free ones you come across.
HiJackThis is an extremely usefull program. The link I provided has a guide on how to use it. Instead of posting your scanlog on an internet forum for someone else to look at for you, you can post your file here,
http://www.hijackthis.de/index.php?langselect=english
and get an automated scan of your file.
Chapter 1 : Bootup
Chapter 2 : Services
Chapter 3 : Drivers
Chapter 4 : Video Card and DirectX
Chapter 5 : Antivirus and Spyware