MSConfig
To access: Start>Run>MSConfig or search for and run msconfig.exe
Shows all the programs which load into system memory upon booting your system. In truth you don't need any of these. WinXP can start and operate 100% without any startup items. For a full list of common startup items and what they do, see this guide or this one. Untick as many of these items as possible. Programs which load at startup take up memory and often cause conflicts while running in the background, especially virus scanners.
You can boost up your startup greatly by unticking these items.