Windows files and settings trasfer wizard help?

my computer is an '04 and it was starting to run slugish and so i, like an idiot used files and settings trasfer wiszard in sted of just copying and pasting files. so i backed up then reinstald and whet to the file and saw alot of .dat files which i have never herd of and i am a little nerdy myself and when i selected it with files and settingins wizard it sayed that thats not a file that contains data please hel i have finace info and 6 months of pic and lots of TXT docs