I prefer Gentoo but thats a biased position.
http://www.gentoo.orgBecarefull, a Gentoo install (well probably any linux install) requires 3 of its own hard drive partitions. 1 partiton for GRUB the boot loader, ~20 megs, 1 drive for swap space (which is optional I think), ~512mb, and one more partition for the os itself. I think that each partition can be its own drive but why bother, also a partition table on any hard drive only allows for 4 partitons.
Here is a screenshot of my diskmgmt software on windows xp:

The grub partition format is ext2 I think, the second partition is swapspace and the 3rd is ext2 the 4th, my windows 98 partiton is FAT32, all formatted with the Linux fdisk application. Linux can read/write pretty much any drive format including mac format stuff. Same goes for removable media. However, NTFS partitions are only readable (no write).
Also, windows XP's boot loader sits on the root of disk 0 called NTLDR, and now, with Windows 98 there, it's own copy of the bootsector from disk C resides there. Normally the user cannot access the MBR, which is what the computer boots. When windows 98 is installed it re-writes the MBR, so then you have to boot into windows XP and restore it to the MBR for dual boot function. Then you use the linux live cd to boot into linux and copy grub into the MBR. Its a fun process.
As for my reason to have windows 98, well its so I can play Sim City 2000 Network edition. I have yet to play. :P Seems like it became more of a crusade XD. My next feat is a new IDE controller card. My old one was malfunctioning and causing excessive heat on my mobo.