There is a lot of information about McMaster's DC++ hub (including instructions on how to get set up) on this thread
In summary, the hub address is machub.dyndns.org and you need at least 500MB of files available to share in order to connect, but the specific details are on that link (you might need to scroll down a bit).
DC++ isn't a resource-heavy program, so slower end computers should be able to run it smoothly. In terms of viruses, when dealing with peer-to-peer file transfers, it's always
good practice to scan everything you download. Fortunately, McMaster students and staff get Sophos anti-virus for free. You can get it here