Partition

If your just going to run Parallels to virtualize Win 7, no need to partition anything. Parallels will create a single file, which will contain all of the data for the virtual machine, so this file can exist on your internal drive or an external drive if need be.

With this setup, you can run Mac OS and another OS at the same time, and share files between them.

 

Just Parallels doesn't require you to partition the drive. And I'm not sure what you mean by 1g...1GB of RAM? if so..i would say probably not...give parallels at least 2GB. And yes any windows 7 disk will work.

 

Also keep in mind, if your planning on gaming, you may want to go with boot camp. Boot camp is where you will dual boot your Mac, this way Windows will get full access to the memory of they system, you can read more here: http://www.apple.com/support/bootcamp/

 

Bootcamp does require a dedicated partition; Parallels does not. In Parallels you can decide how much system memory to give your virtual machine; in Bootcamp it uses all of it. Which is better depends on use (and as noted gaming prefers Bootcamp).

Whether you can use that Windows 7 disk depends on its license. Most PCs are sold now with systems tied to that machine alone. Sometimes you can swap it to a new machine, but you better check with MS before you attempt that. For use with Bootcamp or Parallels some use what are called system builder editions or OEM versions; depending on your use those may work. Otherwise it might have to be the full monty retail version.

Rob