Essential Software/Files

Daily and before doing anything else, run System Mechanic, then update your Windows software, Anti Virus software and Firewall software. Done in the above order, a vast majority of your computer headaches will vanish, immediately. You may have the best car in the world but if you run it on OLD oil and OLD fuel, you will have problems. 

System Mechanic - The only tool you'll need to keep your PC running fast, smooth, and error-free. New PC TotalCare™ combines all of the System Mechanic power into a single one-button interface for the perfect blend of absolute power and effortless simplicity. This tool addresses most PC concerns. 

Windows Update Do NOTHING until you now visit this website daily and update your all of your Windows software. Updating is the most important activity for your computer’s well being. It’s more important than any email message or web page visit, so do this first. 

Zone Alarm - Continually prevents hard-to-remove malicious programs from getting onto your PC and causing damage. I suggest the firewall software and not their antivirus protection. Norton Antivirus is much better.
 
XP Antispy - A free program that disables most of the built in XP spyware that you certainly don’t benefit from, via a tick list that provides you with full control. Each option performed is clearly explained & will be reversible, should need arise. 

PeerGuardian 2 - Some background information on peerguardian this should be used in addition to your home firewall/router and keep the blocklists up-to-date. 

Recommended Files and Websites

Blackviper (use this archived link till site back up) Comprehensive list of Windows 2000/XP services and security settings. 

Misc. Programs

Winrar - A powerful archive manager covers many different formats including winzip. 
Hijackthis - Freeware tool which can be used to detect browser hijacking malware. 
RockXP - Allows retrieval and change to your XP product key. 
Paltalk - Allows you to see, hear, chat and share files with anyone, anywhere in the world. 
Skype - Make calls anywhere in the world over the Internet from the comfort of your pc. 

Security

SecurityFocus - Very informative, scroll down the page for a computer security checklist. 
Symantec Security Scan - (Internet Explorer only) Free service designed to help you understand your computer's exposure to online security intrusions and virus threats.


Antivirus

Bit Defender - Free online virus scanner. 
Trendmicro Housecall - Online scanner checks for virus’s/Spyware/Trojans
Kaspersky - Not free, but it is one of the best AV software on the market.
NOD32 - Again extremely good AV software but not free.
AVG - One of the best FREE antivirus available. 

Spyware/Malware/Grayware/Adware/Trojans

Below are listed suggested utilities to additionally use.
http://www.ewido.net/en/onlinescan/

Adaware SE Personal - Free Anti-Spyware software.
Spybot Search & Destroy - Free Anti-Spyware software.
Windows Defender - Anti-Spyware software (free beta version). 

Registry Cleaner:
Registry Mechanic 5.0 Clean up your registry to improve your system's performance.

Firewall

Windows XP SP2 has its own built in firewall but I strongly suggest turning this off and utilizing Zone Alarm. Free firewall software is not my suggestion. We get what we pay for and when it comes to securing your computer do not cut corners. 

Sygate Free Personal Firewall
Kerio Personal Firewall Free Personal Firewall
Ashampoo Free Personal Firewall
Zone Alarm PF Free Personal Firewall


Internet Browsers

There are quite a few different browsers out there; I recommend these two.
Firefox
Opera 

File Encryption

**Coming Soon

File Deletion

CCleaner

Startup Entries

Hijackthis - Freeware tool which can be used to detect browser hijacking malware. 
http://www.merijn.org/files/startuplist.zip

Port Scanning

GRC ShieldsUP - Excellent online port scanning website; lots of other security tips and advice.

http://www.canyouseeme.org Online port scan 

Proxy 
Using a proxy is very useful; basically it’s like using someone else’s internet.
anonymouse.org 

Media players and Codec’s 
Codec’s are needed to play various media formats.
Winamp Media Player with many plugins and skins
Realplayer Media player
Quicktime Player and Quicktime Alternative codec
Divx - Codec and player
Xvid - Codec only
XP Codec Pack

Links

Various links you may find of use
PC Pitstop - Runs diagnostics on your PC to identify things that might help improve performance. 
EULA - Interesting information regarding the legal jargon you have to sign before installing software.