Please make your recovery disk first, just in case. Also empty temporary internet files, delete cookies, and defrag before continuing.
Back up any crucial data as well, just in case (always think in terms of the worst possible scenario in these cases)
To change from FAT 32 to NTFS file system for more stability, security and less fragmentation, open the command prompt and type:
Convert C: /FS:NTFS
"C" being the drive you wish to convert. Make sure there is a space between the C: and the foward slash (/). Once you press enter it will ask you for confirmation and press Y. Then press Y and enter once more to reboot..
Now thats over
if you are going to merge your partitions then a full format is required or third party partitioning software.