Well, I can tell you how I think you should do it, but you know what they say about opinions
Mount Size FSType Device
/ 1GB ext2 hda1
/boot 128MB ext2 hda2
/usr 2GB ext3 hda3
/tmp 512MB ext3 hda5
/var 2GB ext3 hda6
SWAP 1xRAM swap hda7
/home 2GB ext3 hda8
/fserve1 * ext3 hda9
/fserve2 * ext3 hdb1
/ and /boot can (and likely should) be mounted read only unless you're actively engaged in something that requires changes to them. /boot can additionally have no-exec if you like. /usr can (and again likely should) be mounted read only as well, as there shouldn't be a need to change anything on it once the box is installed (other than updates, but since you'll most likely be interactive with the machine at that point, mount it rw when you're doing that).
Note that /home is 2GB. With a file server (assuming no shell logins) that's probably too much, and you might not need a separate partition at all.
Also, if you're not going to have a bunch of stuff cluttering up /opt, you can go with an even smaller /.
/var should just have log files, so 2GB should be more than enough.
1xRAM means "How much ram you have". So for 512M, swap would be 512M (though you'll probably *never* use that much).
Use the rest of the space for your file serving. THe stuff about /usr and swap being on seperate disks (hda/hdb) and all that is pretty pointless. IDE isn't going to win any races, regardless of how you bust up the partitioning (especially when you break up the FS over two disks on the same cable ...). The reasons to partition wisely are many, but a good one is so that if one FS gets corrupted, it (hopefully) doesn't screw up the whole machine while it's at it. It also makes it easier to change things around and add/remove disks later.
See man hier
for more info (I think Linux still has a hier(7) page ...)
Edit: In case it's not obvious, /fserve1 and /fserve2 are intended to use whatever space is available and be used to store the files you're going to serve. They should probably be no-exec, and maybe read only, but I don't know the specifics of your situation.