Well, I'm not really a pc gamer, so I'm not sure about graphics cards and stuff, but my main emulation console is my samsung galaxy note 2 with a 60 gig card (those psp and psx roms are BIG) There's a brilliant range of emulators for android devices, and joysticks, etc. There is rumoured to be a GameCube emulator on the cards, but the current tech probably isn't powerful enough to handle it. It's called dolphin, I'm sure it would work on your pc, though with your specs. (It's the epsxe app I'm using btw).
I've always been a console gamer myself; just buy the machine and your good to go - no need to upgrade the internals. Course, even the next gen consoles are simply incapable of matching a really good PC game rig, some of the graphics on those are just astounding. PC gaming is something I would love to get in on, but I just don't have the budget for a really good rig.
Edit: as pointed out, kingdom hearts is an amazing RPG; I'm playing it on my ps2 at the mo. It's pretty much a hybrid of a a FF rpg, starring many of its characters including cloud, and those classic Disney platformers such as alladin, the lion king, etc way back from the 16 bit days.