PGDSpider: an automated data conversion tool.

"The analysis of genetic data often requires a combination of several approaches using different and sometimes incompatible programs. In order to facilitate data exchange and file conversions between population genetics programs, we introduce PGDSpider, a Java program that can read 27 different file formats and export data into 29, partially overlapping, other file formats. The PGDSpider package includes both an intuitive graphical user interface and a command-line version allowing its integration in complex data analysis pipelines."

"PGDSpider is a powerful automated data conversion tool for population genetic and genomics programs. It facilitates the data exchange possibilities between programs for a vast range of data types (e.g. DNA, RNA, NGS, microsatellite, SNP, RFLP, AFLP, multi-allelic data, allele frequency or genetic distances)."

Haven't tried this converting software yet but is freely available here:
http://cmpg.unibe.ch/software/PGDSpider/

It supports a wide variety of file formats including PED and FASTA.