Once done, I would recommend SimplyMepis as the Linux choice. I've done dual boot with Ubuntu also. I like SimplyMepis better. It handled my wireless interface flawlessly where Ubuntu had to tweaked, prodded and cajoled.
The best website I found for a step by step guide is here:
Creating a Dual-Boot Windows XP and Ubuntu Laptop
It's for Ubuntu but can be used for other distros.
Good luck!
Bookmark for tonight’s project.