I have dx9 level graphic card installed but unity says that it is required?

GREETING

I have unity web player version 5.1f1 installed on my computer everything was alright when one day i tried opening a game , it said "unity web player requires dx9 level graphic card make sure you have the card installed". then i opened dxdiag it said Operating System: Windows XP Professional (5.1, Build 2600) Service Pack 3 (2600.xpsp_sp3_qfe.120504-1617) Language: English (Regional Setting: English) System Manufacturer: Dell Computer Corporation System Model: OptiPlex GX260 BIOS: Default System BIOS Processor: Intel(R) Pentium(R) 4 CPU 2.53GHz Memory: 766MB RAM Page File: 628MB used, 1247MB available Windows Dir: C:\WINDOWS DirectX Version: DirectX 9.0c (4.09.0000.0904) DX Setup Parameters: Not found DxDiag Version: 5.03.2600.5512 32bit Unicode

everything seems fine i have tried uninstalling reinstalling but nothing worked Please HELP I am stuck.