Reformating or deleting the partitions WILL NOT stop someone from getting info off the disk, all either does is reset flags that the DOS uses to find out head position on disk. There are numerous programs on the NET to get your info back when a reformat or deletion of partitions is done by accident or on purpose.
There are also many programs to run on it to completely erase(actually overwrite) your disk and will write ones and zeros over and over again to make sure the disk is blank. One is killdisk.com they use the same as the government uses as well as many others. I would suggest using one of these methods to make sure what ever info you use cannot be used!!!!