Here is my fileserver setup, don't know if this helps though...
md0 -> hd[a/c]1 -> /boot
md1 -> hd[a/c]2 -> /home
md2 -> hd[a/c]3 -> /
swap -> ~2x(your amount of RAM)
From what i have read, the swap partition is similar to window's virtual memory; it's already RAID0. You do not have to create a RAID partition for swap.
Say you have 256MB of RAM, you can put 256MB into hda and the other 256MB into hdc, which totals up to be 512MB. (FYI, my CD-RW has taken hdb).
For RAID1 to work, say you have a 80GB hda and an 40GB hdc, you can only mirror up to 40GB. I tried this with 2 similar HDD, going to try HDD with different sizes today.
Please correct me if I'm wrong (as usual
), hope to get some feedback whether i am on the right track myself!