I've been doing a little cleaning and minor upgrading to an old Dell Dimensions 3000, with a P4 3.2GHz, I had laying around (was a little bored ) for my youngest son. I've switched out the stock cooler with a Thermaltake TR2-M12, new 500GB IDE hard drive, up the RAM to 1GB and I thought about adding an a PCI slot GPU. The system is running a lot faster with the new hard drive than it was went I got it from a friend a while back. My next logical choose would be add a GPU to help give it a little more graphics power. Here are some GPU's I was looking at and wanted your feedback!
those cards are PCI not PCI-E so I'm assuming Dimension 3000's don't have a AGP slot (nor a PCI-E slot).
In that case, I'm fairly certain the PCI video card will be fairly bottlenecked. that slot usually only has 33MHz bus. The integrated graphics probably runs on an internal AGP bus, even if there's no slot so it has a lot more bandwidth to play with.
You might want to go cheaper than a 9400GT if you can. It might not make a difference. If I had to pick from those 2, I'd go with the 8400GS since it's cheap. Or even stick with the integrated solution since it's probably fine for 2D.
On the other hand, for the money you'd spend on a PCI GPU upgrade, you may be able to score a barebones case/mobo/psu (maybe even a P4 775 CPU) that is more upgradeable. Reuse the RAM and opticals and you'd be in good shape (for a P4 at least). Just a thought.