i work both machines the same !!!

i have on the hd lots of backups and i burn from them!!

both pc's work 24/7
both pc's are workin at least 15hrs a day

i dont know what to do?i keep finding the drives losing data,or windows is telling me the drive is not formated?
could anyone give me some info on mass storage?thats reliable?

i have been transfering data big amountsof data fromsome old drives to the new 250gb hd's can this creat any problems?????