Is there a way to dual boot my mac mini to run Lion & Headless NAS?

I only use my mac mini to download torrents & surf some websites that are broken on my iPad.

My mac mini has got old & it keeps overheating & crashing.

Is there a solution where I can run my mac mini in NAS headless mode for downloading torrents.

When I need to use my mac mini for browsing some sites that don't work in my iPad, I could just boot into the lion partition.

For the rest of the time, I want to be able to run my mac mini in headless NAS server mode to download torrents 24*7

NAS server mode would presumbly be less of a CPU resource hog on my 5 year old mac mini2,1

Is it possible to do that?