Creating a virtual machine to test things is a briliant idea, I wish more people would do that instead of corrupting their main install. If it is possible for your use case, most probably YES, but you're not being very specific. If you know you want an extra partition on forehand, you can create it during install of the VM. VirtualBox is a good application for running VM's and it is in the standard repositories.
The fun about virtual machines is that you can completely mess up things inside a VM, while your host OS stays up running stable. Worst case scenario is that it runs somewhat slower because the VM is using a lot of CPU or (disk) IO.
Personally I always have a few VM's installed, just to test things.
In many modern PC's you can enable VT-x or AMD-V extensions, which will dramatically improve performance of virtual machines. Refer to the manual of your motherboard for this.