General call for nerdy help. I'm planning on getting a new PC half way through this year. It's been five years since I bought my last PC so I'm way out of date on the technology jargon.

My current PC (P4 2.4Ghz, 1Gb RAM) is plenty fast enough, it's just the motherboard that is out of date. I need to get a new graphics card (so I can play Portal) but my motherboard only supports PCI and AGP (x4), while all the new graphics cards are PCI-E or AGPx8. Being able to use SATAII hard drives would be a bonus too.

Or... would I be better off just getting a new motherboard? Could I just get a new motherboard with the PCI-E/PCI slots I need and plug my old CPU/memory etc. into it?

Any recommendations or warnings would be appreciated.