simple website just google : Can I run it?
Yes any decent video card can run DayZ. If you go cheapo, then NO it won't run it well.
As for 'i know nothing about pcs' - Give you two choices then, do what everyone else and GOOGLE for professional company / websites that DO know about PCs and READ the articles, testing, reviews and make a responsible choice OR sell off the PC as it requires ALOT of maintenance, upkeep, and 'you need to know about PCs' to keep it running correctly; most people are VERY comfy with consoles because it is SO MUCH EASIER then trying to patch PCs, virus scan, keep malware off, find updates, clean out the PC, monitor temps, and so on and so forth.