Hey Anusha,
Converting a fat/fat32 HDD to ntfs using Windows, always converts it to a NTFS partition of 512b as the cluster size -- Personal Experience...
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To convert a volume to NTFS from the command prompt
Open Command Prompt.
In the command prompt window, type
convert drive_letter: /fs:ntfs
For example, typing convert D: /fs:ntfs would format drive D: with the ntfs format.
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Once I had Windows 2000 in FAT32 and that's where i tried the command prompt thing. I didn't like this as you don't. So I had to format it using Windows XP CD and installed Windows XP. When you full format the partition, it formats as 4069b per cluster. I don't know why it doesn't happen to you...
Tell us the partition details of your HDD. How many partitions, and the file systems, the cluster size etc more vividly...