Hi, yes that PSU will work with AGP. PCIe cables are just for newer setups PCI-Express graphics cards. It's also modular which is a good thing, keep it lookin tidier and better air flow.It's also 85% efficent which is pretty good. Coolmaster are quite a well known company and do manufacture quality components.
Only main change was from 20 pin atx to 24 pin atx and a few 8 pin power connectors. If a new type of power connector did come out you could always get an adapter for it, e.g. molex to sata, molex to 6 pin, molex to 8 pin, molex to fan etc.