It is very likely that when your styles were copied over, the fonts they require may not have accompanied them. In order for the marker symbols (especially) to appear correctly, both items must be install.
The older version (9.3) style will open in 10x but it will not be available in the same way as in 9.3 after being opened in 10x due to schema having been added in 10x.
This is what I could find, styles PDF for 9.3;
http://downloads2.esri.com/MappingCenter2007/arcGISResources/more/ArcGIS_v93_Styles.PDF