Being draconian in only allowing one platform or sticking resolutely to the same software that you purchased five years ago that hasn't kept with the times will discourage rather than encourage younger volunteers. Or, if you have focused on the PC side, you will likely limit the artistically minded who can really add to your visual or aural dimension as they tend to be Mac users. Budget limitations and your ministry demographic notwithstanding.
One Bible camp purchased several PC based systems to develop DVD's for the campers several years ago. Fast forward this past summer and most of the editing were done on Macs that volunteers brought to camp while the PC's sat gathering dust. Now anytime you work with huge video files, you're going to have a program crash on you. With the PC's, the crashes would sometimes require a complete system rebuild as the hard drive became corrupt beyond repair. With the Macs, a simple restart of the the program usually was all that was required, although in a couple of cases, some re-editing had to be redone.
Now I understand that the director wants to move this part of the ministry to Macs next year as soon as donations or budget allows. The still useful PC's will be repurposed in a different role.
Instead of swimming upstream, you might want to ride the tide of growing Mac usage.