I have a laptop with the 4500MHD, and it does support DXVA from MPC-HC's internal decoders.. beats me how, but it does.
Under Ctrl + J in MPC, it says DXVA2: H.264 bitstream decoder, ClearVideo(tm)
Also, if the computer with the 4500MHD comes with Windows 7, use the Microsoft DTV-DVD Video Decoder for DXVA instead of MPC-HC's internal DXVA filter as MPC's internal DXVA filter does not appear to support deblocking with the 4500MHD, which will show artifacts in video.
My DXVA guide/reminder to self:
http://www.cccp-project.net/forums/i...29294#msg29294