Erm dude.. you know for a big game like this, typical search like "ff14 client download" would instantly yield you the result? The first link by entering this on a search engine leads you directly to the link:

http://www.finalfantasyxiv.com/playersdownload/na/

And BTW you can also port over your char config/HUD over by saving the folder "Documents\My Games\FINAL FANTASY XIV - A Realm Reborn" into a thumbdrive and paste it to the same directory in your new PC. Saves you shit ton of time on your new com to get back the same layout.