well for the 5gig partitions you can use 4k, or even 2k.
same for the win2k partition.
or i suggest you go for NTFS on that one... unless you transfer alot of data between the two.
as for the 30gig partition,
i would suggest NTFS, but thats just the advice of my win2k junkie hamster beside me
and u cant access a ntfs partition from win98.
so i would go for 16k or 32k clusters.
typically when u do a standard format of a fat32 drive the cluster size depends on the size.
eg. up to 4gig = 4k clusters
4 to 8gig = 8k
8 to 16gig = 16
16 to 32gig = 32 etc
your call on the last one.
as drives are pretty fast nowerdays u could use 16k happily. less space wastage
My Hamster has 512MB of SDRAM @ 150Mhz CAS 2!