Help with Virtual PC 2007

I have 20 gig external usb hard drive that I need to configure to run 4 Virtual PCs running XP Pro and I wanted to know whether its possible to install all 4 on the one hard drive and also can I clone 1 of them to make the other 3 to save me time of installing all the machines 1 by 1. If virtual Pc2007 cannot do the job can you recommend other free software that me able to do that for me because I need the Vpc to study for the MCSA server exams. I have had of network simulation but I think I might have to pay for that.
Comments
Just bear in mind if you copy the machine settings files and Virtual HDD you will need to remove the VM from any domain and rename it prior to adding it back to the domain.
1. Get a VM up and running the way you like it.
2. Copy Sysprep and its dependent files into C:\Sysprep (you want it in here cause Windows knows to remove this directory after Sysprep is run)
3. Use Setupmanager to create a sysprep.inf to help with automation.
4. Place the sysprep.info in C:\Sysprep
5. Run Sysprep
6. After Sysprep is run, copy the .vhd file to a separate location.
7. Create a new folder for your 2nd VM and copy your .vhd file into this folder.
8. Create VM2 and tell it to use the new copied VHD.
9. Launch the VM and it will launch the OS and run Sysprep.inf for unattended configuration
10. Repeat steps 7-9 for your other VMs
VMware Workstation has a cloning feature so once you get to step 5, you can just keep the VM shut down. Then for new VMs, you can just clone the Sysprep'd image. No copying/pasting needed.
The problem with this approach is that all the machines will literally be identical (i.e. they'll have the same SID, etc.), which can be problematic. I cloned a few machines in VMWare like this, and I ran into all sorts of problems. The machines will function fine separately, but you'll go insane once you setup domain controllers that are interacting with each other, etc. This method simply gives each machine unique information.
I don't think you have any reason to feel stupid. I was pulling my hair out until I stepped back and thought about what I did. It's not an obvious issue.
Speaking of which, I did this for Server 2008 because getting a sysprep.xml file created is a huge PITA. I just cloned them all with the same SID and just used Sysinternals NewSID.
In Server 2008, you have to download the Windows Automated Installation Toolkit (1GB), which contains the utility necessary to create a Sysprep.xml. You then have to burn this ISO and then launch it on a Native Server 2008 machine. Since I didn't have a Server 2008 host and didn't want to bother installing the entire WAIK on a guest, I just did the NewSID. Seriously, why the hell did they make it so difficult to just create a Sysprep unattend file.