Here are some more tips.I am providing 8 more steps
11.) Remove any unnecessary programs and/or items from Windows Startup routine using the MSCONFIG utility. Here’s how: First, click Start, click Run, type MSCONFIG, and click OK. Click the Startup tab, then uncheck any items you don’t want to start when Windows starts. Unsure what some items are? Visit the WinTasks Process Library. It contains known system processes, applications, as well as spyware references and explanations. Or quickly identify them by searching for the filenames using Google or another Web search engine.
12.) Remove any unnecessary or unused programs from the Add/Remove Programs section of the Control Panel.
13.) Turn off any and all unnecessary animations, and disable active desktop. In fact, for optimal performance, turn off all animations. Windows XP offers many different settings in this area. Here’s how to do it: First click on the System icon in the Control Panel. Next, click on the Advanced tab. Select the Settings button located under Performance. Feel free to play around with the options offered here, as nothing you can change will alter the reliability of the computer -- only its responsiveness
15.) Visit Microsoft’s Windows update site regularly, and download all updates labeled Critical. Download any optional updates at your discretion.
16.) Update the customer’s anti-virus software on a weekly, even daily, basis. Make sure they have only one anti-virus software package installed. Mixing anti-virus software is a sure way to spell disaster for performance and reliability.
17.) Make sure the customer has fewer than 500 type fonts installed on their computer. The more fonts they have, the slower the system will become. While Windows XP handles fonts much more efficiently than did the previous versions of Windows, too many fonts -- that is, anything over 500 -- will noticeably tax the system.
18.) Do not partition the hard drive. Windows XP’s NTFS file system runs more efficiently on one large partition. The data is no safer on a separate partition, and a reformat is never necessary to reinstall an operating system. The same excuses people offer for using partitions apply to using a folder instead. For example, instead of putting all your data on the D: drive, put it in a folder called "D drive." You’ll achieve the same organizational benefits that a separate partition offers, but without the degradation in system performance. Also, your free space won’t be limited by the size of the partition; instead, it will be limited by the size of the entire hard drive. This means you won’t need to resize any partitions, ever. That task can be time-consuming and also can result in lost data.