Most are free and will run well under any P4. You could also run Sun's VirtualBox software on the W7 system then load Ubuntu as a virtual machine. Both are free. You can then download and run any other version of Linux such as Mint and run them as additional VMs. No need to wipe the system clean and reload a different flavor. BTW, Mint may be the better choice for you if you want to work with a lot of multimedia stuff.
