I have an older Dell Dimension 8400 with a 3.0GHz Pentium 4 Prescott, with 128MB Radeon X300 connected by PCI-Express, and I prefer to shop on eBay, under $65. Looking at the different graphics cards, I am not fully sure on what I should be looking for exactly, amount of VRAM, core clock, or what?
for a better price. It would outperform the other cards you had listed and uses very little power. According to one set of specs i saw on the Dell 8400 it has a 350w power supply, the HD4670 would be fine for that supply.
it does have a 350W, and i prefer one with a vga built in,forgot to mention that, and those are all too expensive on ebay, and i'm not an extreme gamer, but i do, casually, and i am thinking that any of these would be a huge step above what i have now. what i really want to know is which of the ebay ones will give me the most bang for my buck? and will there be bottlenecks with my current setup? is there a difference between PCI-Express and PCI-Express 2.0?
Which is much faster. Below this, the best options are the Radeon 4650 or the nVidia 9500GT. Either the 4650 or the 9500GT would generally be faster than the 3650 and much faster than the other cards you listed.
It may be surprising, but often you can find better prices at newegg then you can find on ebay. It may be that you're outside of the US and can't use newegg, there may be other retailers that can offer better deals. The HD4670 is not a high speed gaming card, but it is adequate for a low powered fairly inexpensive graphic card. If the price is just too high, then the HD4650 would be a better choice then the others you had listed. Also some graphic card manufacturers will not warranty cards purchased on ebay, not even new ones, they have to come for a regular retailer. Make sure you check with whichever manufactures card you get to insure it's still covered by a warranty.