The following was borrowed/stolen from:
19 Ways to Speed Up Windows XP
Also visit Black Viper for Windows XP configurations.
C Cleaner. C Cleaner is a little program that will help you clean out extraneous entries that might have cropped up in your registry. Many times when you delete a program, registry keys could be left behind. Tracking them down manually can be tedious, this program scans your system and does it for you. It also does the same for your hard drive, potentially freeing up GBs worth of space.
Service Pack 3. One of the simplest ways to speed up your system is to install Service Pack 3. Some people report up to 10% performance improvements as a result.
Remove Spyware / Malware. This is the old standby. Adware, Malware and Spyware will slow down your computer and can cause all sorts of other problems besides. Take some time to download an Adware scanner like Spybot or AdAware and clean your system.
NTFS instead of FAT32. Make certain that your hard drive is using the NTFS file system. To convert to NTFS, use the following steps:
TweakXp. For advanced users, TweakXP can be an incredible boon. TweakXp makes it easy to turn on and off dozens of registry tweaks that can help speed up your system. Fair warning, if you aren’t sure what you’re doing this is also a really great way to degrade your performance or damage your system.
Disable Indexing. Windows automatically indexes files to make searching faster. This can cause major slowdowns and is often unnecessary. If you don’t use search often, feel free to disable it by following these steps:
Optimize Display. If you are really trying to squeeze out the last drops of performance, you can cut down on some of XP’s visual flash by optimizing your display settings. Play around with the options, nothing you do here is going to damage the system, and disabling many of these settings will cause a noticeable improvement in speed. Here is how to access these settings.
Disable Performance Counters. Windows has several tools to track the performance of your system and display the results in graph form. If you don’t use this information, disabling the services can help to speed up your system. The easiest way to do this is by downloading Microsoft’s Extensible Performance Counters List and using it to disable the performance counters.
Cacheman. Cacheman is a program that can help you manage your memory, it allows you to automatically recover RAM from programs that are sitting idle, and provides superior paging file management.
Driver Updates. Make certain that your BIOS, Video Card, and motherboard chipset are up to date. Here are some tips on upgrading Your BIOS.
Disable Unnecessary Ports. There is a good chance that you have a few ports that you won’t be using anytime soon. In most cases, you can safely disable these without causing any troubles. As always, be extremely careful when you go around playing with your BIOS.
If you feel comfortable doing this, access your BIOS from the boot screen.
Empty Your Prefetch Folder. Windows uses the Prefetch folder to store data that it uses often. Unfortunately, over time this folder will become filled with programs and data that you no longer use. Emptying your Pre-Fetch folder every few months will save you a few cycles as Windows won’t be loading data that it no longer actively uses. You can find your prefetch at:
/windows/prefetch
Run Disk Cleanup. Once a month or so it’s a good idea to run disk cleanup.
Remove Unnecessary Programs. Stop being a packrat, remove the programs that you aren’t using from Add/Remove. You’d be surprised how much disk space there is to recover in the software that you never use.
Disable Your Background. If you care about speed over beauty, disable your background image. Images will slow boot time and reduce performance.
Fonts. Make certain that you have fewer than 500 fonts on your system. Especially if you don’t use them all, fonts can be taxing to your system. Delete the ones that you don’t need for a slight bump in performance.
Disable unnecessary services. Unnecessary services waste cycles, disable the ones that you don’t need. Once again, this can be dangerous if you don’t know what you’re doing. Take a look at Black Viper’s site for some helpful hints.
Reduce Your Recycling Bin Reserve. Right click on your recycling bin and select properties, what you’ll notice is that about 10% of your hard drive is reserved to be used to store deleted files. Unless you typical delete massive files, this is overkill. Reduce the size of this reserve to 2-3%, a much more reasonable value.
Busmaster Drivers. Find and update the Bus Master drivers for your IDE controller. To find out what type of IDE controller you have: