|If you need FAT32 then there is no way around it. Do you use the drive for other stuff too? You could partition the drive into at least 2 partitions and use one for the PS3 and format the other NTFS.|
If you need the entire capacity for the PS3 then don't worry about it.
To explain impact what cluster size has I will give an example. Writing a file 1Kb in size to an NTFS formatted partition will waste 3Kb of space because a cluster can only hold 1 file. Writing that same 1Kb file to your 1TB partition using FAT32 will waste 31Kb of space because the cluster size is 32Kb.
If the individual files you are writing to the 1TB are large then this becomes less of an issue. Large files may use multiple clusters and the odd change at the end may be the only cluster with any appreciable slack space.
Hope this make it clearer to you.