when i remember correctly, KH2 MDLX models does only work with the d3d9 version of modelviewerWX.
throw them into the grey window, when nothing appears then maybe your graphic card is the problem due lack of pixelshaders.
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My System: C2D E6700 @3.4ghz | Asus P5W DH Deluxe | 4GB DDR2 800 | eVGA Geforce GTX 260 55nm SC-Edition
Tutorial: Hardware Antialiasing in PCSX2 (DX9 only)