It's not a bad idea. If you look at about any profile of an attorney at a large firm, most will say Phi Delta Phi or Phi Alpha Delta. However, Phi Delta Phi is at most schools an Honors Fraternity, so it may be viewed in a little higher regard than Phi Alpha Delta, but not by much.
Wait until after your first semester grades and then join Phi Delta Phi if you can, but if you can't then at least join Phi Alpha Delta. Hillary Clinton was a member so it can't be that bad right?