4k is supposed to be the best, as the intel (and presumably all i386's) handle data in "pages" of 4 kb. It's definitely better to have the page file on a partition with a 4k cluster size, as there would be extra read and write operations to convert to cluster size otherwise. I don't know if this applies to other files or not, but I'd imagine there would be some other benifits to 4k (which seems to be the default NTFS cluster size anyway).