First: You need lots of RAM to run a Windows virtual machine with decent performance. How much RAM does your mini have?

If you run a virtual machine configured with 2GB of RAM, then VMware will use 2GB of RAM plus whatever overhead the VMware app itself needs.

I'd say 4GB is the bare minimum for using a virtual machine, and more is better. (I have 8GB, and that works nicely.)

Of course, it also depends on whether or not you like to leave multiple apps open simultaneously. I do, so more RAM is better.

The downside of using Bootcamp is this:
If you do NOT use Bootcamp, then VMware can suspend your Windows virtual machine when you quit VMware. And then just resume that virtual machine the next time you launch VMware.

But if you use VMware with Bootcamp, you'll need to shut Windows down every time you quit VMware.