SYSTEM TOOLS:

MSCONFIG -> Slow boot problem; changing startup apps or sequence; multi-boot config

DXDIAG -> DirectX diagnostic tool to fix problems with high quality graphics etc

REGEDIT or REGEDT32 32 -> bit Registry Editor for advanced user fine tuning

MSINFO32 -> Microsoft System Information Tool

GPEDIT.MSC -> Microsoft Group Policy Editor: Full featured XP configuration tool