I think the best way is ArcGIS. in Arcmap module by using Tools Box convert dxf to shp file. if you want know detail please call me. for converting xls file, the first add it to arcMap then by right click and select Display XY Data do it
If you want free/open source use ogr (http://www.gdal.org/ogr/). The utility ogr2ogr can inter-convert a large number of vector formats including DXF and TXT (comma separated.) See "http://www.gdal.org/ogr/ogr_formats.html"