MediaSmart is not the same as Windows Media Center, it is sort of more like HP's multimedia extension developed by Cyberlink -- it used to formerly be HP QuickPlay/DVD Play.
SmartMenu is posted online on HP's website (and is now on the original post). Try the one that HP has provided online:
ftp://ftp.hp.com/pub/softpaq/sp42001-42500/sp42238.exe