- Defrag Your Harddisk(s)
Frequency : weekly/monthly
Defragging your harddisk makes access to files faster. Do regular defrag to get maximum performance of your harddisk. Personally, I don't recommend defragging using Windows' default disk defragmenter, try using program such as Defraggler, JKDefrag, or etc. (Defraggler is my favourite!) - Tweak and clean registry
Frequency : daily
Registry is important part of Windows, by cleaning registry with tools such as Eusing Registry Cleaner, it will search for invalid registry, errors and perform cleanup. - Delete junk and unneeded files from harddisk(s)
Frequency : weekly/monthly
Junk and unneeded files or programs suffocates your PC and waste diskspace. Regularly delete them and use Windows' Disk Clean up to perform such of these actions, or 3rd party software such as CCleaner to get even better result. - Delete Prefetch files
Frequency : weekly/monthly
The prefetch folder is used to help speed up the loading of programs XP will load programs it thinks you need before you ask for them yourself. But time to time it will overloads, so go to your Windows folder, look for prefetch folder and delete all files in that folder. - Clean and optimize RAM
Frequency : frequently/when needed
When you close program, sometimes it fails to release itself from memory. By time to time, it consumes precious space in RAM and makes PC slower. Clear or optimize your memory using tools such as RAMBooster. - Install antivirus and antispyware program
Frequency : once LOL...
Install antivirus and antispyware program to keep your PC safe. If you find out that paywares are too expensive, there's also great free antivirus such as Avira, AVG, etc. and regularly update them (My recommendation is install Avira, Spybot, AdAware, and Spyware Blater. They're rock!). Note : Spyware blaster don't remove spyware, it prevents spyware installed in your PC. Spybot detects most dangerous thread, but AdAware detects more dangerous cookie, so use both. - Scan PC for threats
Frequency : monthly/when needed
After downloading antivirus, it is a must to do a regular scan. Make note to update the program before scanning and turn off System restore before removing virus. - Optimize visual effects, virtual memory, and processor usage
Frequency : once/when new memory sticks added
First, go to Control Panel->System->Advanced (tab)->Performance, click settings.
Disable un-needed visual effects that you dont need such as animation when maximize and minimizing and other (yours to choose).
Then go to advanced (tab), set both processor scheduling and memory usage to program if you want to make foreground program runs faster, and background to make background process faster. (I recommend program).
Wait, not done yet change virtual memory, select drive that contains paging file. Set initial size 1.5 times as your actual RAM (if you have 1 GB ram, set it to 1500. 1000x1.5 = 1500) and set maximum size 2 times of initial size. - Disable useless startup
Frequency : when needed
We don't need all programs to run at startup, it will take time to run, so go to run, type "msconfig" without quotes. Then a new window comes up, go to startup, untick un-needed programs and click apply (some program is REALLY required to run at boot, dont mess up with something you dont know. Google the process name to specify whether it is safe to disable or not). - Disable Windows service
Frequency : once/when needed
Not going to say much about this, we dont need useless Windows services, so better turn it off to gain performance. Go to run, type msconfig, go to services, untick un-needed services and click apply, then go again to control panel->administrative tools->services. Stop the same services you untick.
Lists of service which safe to stop can be searched in Google or in here : http://www.optimizingpc.com/optimize/windowsservices.html
Sorry, there's too many, I can't type it all!
Hopefully it helps


