Clustal W is a general purpose multiple sequence alignment program for DNA or proteins.It produces biologically meaningful multiple sequence alignments of divergent sequences. It calculates the best match for the selected sequences, and lines them up so that the identities, similarities and differences can be seen. Evolutionary relationships can be seen via viewing Cladograms or Phylograms.

You can use it online :
  in Lille
  at Pasteur Paris
  at the PRABI
  in Bordeaux
  at EMBL - EBI, where it is developped.