Right, well the good news is, your Idea is possible, i run a Dual-boot Xp/Mandrake9 system. Here is how i did it.
1. Install Windows
2. Install Linux :x
3. When installing Linux make sure Boot Loader goes in /Hda and not Hda2/3/4/5/6/7 etc. And everything will work as planned, pick your OS at boot time, for your purposes I would recommend setting Windows as default boot during installation, have fun!
Graham McMaster