Either would be fine, but Mandrake is more new user friendly. I would suggest putting the boot manager for Mandrake (Grub in it case) on the master boot record.
Also, only format one harddrive for windows. Don't even partition the one you want to put Linux on. This will save you a lot of trouble with trying to find space during the Linux install.
For the partitions:
512MB or 1GB swap
everything else /
or
512MB or 1GB swap
20GB /
everything else /home
or
512MB or 1GB swap
10GB /
20GB /usr
everything else /home
depending on your preference. I use the 1st with Gentoo, but these are just guidelines. Do whatever you feel is best. /Home holds are your personal stuff, /usr holds all the system wide programs, and / holds everything. If you download a lot of stuff, increase /home, if you like to install a lot of programs, increase /usr.
If anything goes wrong and you can't boot (this shouldn't happen, but you may need to know this in the future anyway) boot off the WindowsXP install CD, choose Repair or Recover from the menu (can't remember which one it lists, but it is one of these) and run these commands from the Repair Console:
fixmbr
fixboot
That will remove Grub or Lilo and reinstall the windows bootloader.
