most basic setup is to have a / and swap partition yes. If you only use primary partitions this is most easy setup:
hda1 swap for linux
hda2 / for linux root filesystem
hda3 winXP HE
hda4 left-over (it's nice to have 1 fat32 partition if you want to exchange files between the systems, because winxp and linux can read/write to it)
(replace hdaX with your harddrive / partitions)
I think it's easiest to use the grub bootloader, it's perfectly able to boot windows XP (don't know the exact config, I'm not a grub-user). Basicly grub just starts the winXP bootloader if I'm not completely mistaken...
Also note: it's easiest to install windows first, because it overrides your mbr. If you installed linux before windows, you lost the mbr and you'll have to recover it with a linux CD to re-install grub on it.
I also found a small guide on using the windowsXP bootloader to boot linux: bootloader guide
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