At first glance I think this is a good budget set up but if you are looking for 60 fps in 25 mans it probably won't cut it. Maybe 30 fps on good or high in 25 mans. Out in the open world this set up will work very well but 25 mans are hard on any budget system.
You'll be able to play on medium to good settings, just turn down shadows. The graphics card is bottle necking you the most but for 25 man, both the gpu and processor will be holding you back in intense combat due to particle effects