I just need to ask a quick question, I lent my friend my Kingston 8 GB DataTraveller for copying some ISO file (or ZIP? I dont exactly remember) but he said he is not able to copy that 6.21GBs data to the stick as he's getting an error "Cannot copy files due to low disk space..." or something like that. He was using Windows Vista, must be professional or ultimate as he was at his workplace.
The only reason that I can think of is the file size restriction in FAT32 file system (He formatted the drive using this FS). Can there be any other reason except that?
"The maximum possible size for a file on a FAT32 volume is 4 GB minus 1 byte or 4 294 967 295 (232−1) bytes." From the sometimes-reliable Wikipedia.
As to your 8 GB drive being a 7.45 GB drive, there are two reasons. First, manufacturers measure GB in 10^9 bytes, but computers measure it in 2^30 bytes. A manufacturer's kilo- is 1000, while a computer's kilo- is 1024.
Secondly, some of the storage may be dedicated to replacement blocks, formatting, housekeeping, or the storage fairy.