I would upgrade from that PC either, unless you go for a fast quadcore (i5/i7 in Intel range) or something even more expensive (not recommended). If you don't need it for playback of anime, no need to upgrade, right

At this point, new video formats are coming that might need more cpu power to decode.
We don't know yet how slow will decoding H.265 be in practice, and we also don't know if fansubs will use the 10-bit profile (if a usable encoder supports it...). I get PC hardware for several years, and right now it is not clear how strong CPU will be needed, so not a good time for upgrading, unless one really has to. Hopefully we will see in 2 years
