I've had 3 PC's for the 1 MAC I purchased. Mac out-performs everywhere. I have my HD partitioned to allow me to run windows when needed.
If you want a desktop, pick up an iMac, they're extremely powerful and partition Windows on the HD with the drivers. It works great.
I don't download anything on the windows side without doing some serious research. On the Mac side I can be more lax to downloading files, less fear of viruses.