There's lots of guides on the internet for setting up a raw disk image for qemu using an install disk, but I haven't really been able to find one that details how to do so with a partition that already exists. Supposedly, qemu is able to boot directly from /dev/hda1, but I can't figure that out. Everytime I try (qemu -hda /dev/hda, or qemu -hda /dev/hda1, I wasn't sure, but neither worked), qemu starts up but gets stuck on "Booting hard disk..." and just sits there.

I think it's not finding a MBR, or something along those lines. I dd'd an image of my partition (Windows XP), but that doesn't seem to help any. I'm new to this virtualization stuff, so I'm sorry I'm way off track.

My computer:
2.6.27.21-170.2.56.fc10 x86_64 GNU/Linux

Hmmmm, I've never tried that-Your talking about a VHD on your HD-yes?

What do you mean by "but I haven't really been able to find one that details how to do so with a partition that already exists."

Clarify please...

Also, my dsl/qemu stuff uses the "KNOPPIX" cloop image as "-hda DSL/KNOPPIX"
And where "-hdb hdb/HDB" is the vhd I made for it in a folder named "hdb"
And it all runs from USB or out of the folder on your desktop
AND it has persistent save!
Start it with "./mydsl.sh"(double-click-select "run"), add some mydsl apps/themes and shutdown/backup and all your stuff's there!
Additionally-put whole DSL-embedded-persistent.zip on your USB, install syslinux, set boot flag and reboot
At the DSL live desktop, open a root shell(terminal), type "mount" to find where the usb is mounted(usually "/cdrom" or "/mnt/auto/cdrom"
Then type "cd /cdrom"
Then "./mydsl.sh"
Bang!
DSL-Qemu inside the DSL live desktop!

Basically I've got a Windows XP partition and a Fedora 10 partition, and I can dual-boot to either one. I'd like to be able to continue booting into the Windows partition normally so I can play games (I hear qemu really cuts down on processing speed), but I'd also like to be able to run that same Windows partition as a virtual machine while I'm running Fedora, so that I can do some Windows only stuff without having to reboot my computer. I've found tons of guides on the internet for making a windows virtual machine, but none on doing what I want to do.