Neither is gonna be specific to AMD processors or Intel. But I would suggest just being smart. Use a page like www.pricewatch.com to search for the best prices.
And don't listen to the ATI or Nvidia fanboys, they're in a never ending battle. I prefer ATI because of their All-In-Wonder series, but I'm currently using a GeForce 4 Ti 4400. It's a great card, and I'm using it with an old P3 450. I get playable framerates in all the games that I want to play (Zelda, Golden Eye, Perfect Dark, SSB, etc.) So just find a brand that you like in your price range, and look at a review site such as www.tomshardware.com, and see how good it compares to the competition in it's class.
I would also suggest going with a more total upgrade than just your v-card. If you can afford the update the mobo, memory, cpu, and v-card. Which with a $500 budget, you could do really well with a AMD setup, and still have enough for a great v-card. But don't blow it all on the card, as someone said, it will really bottleneck the performance of your system.
And don't listen to the ATI or Nvidia fanboys, they're in a never ending battle. I prefer ATI because of their All-In-Wonder series, but I'm currently using a GeForce 4 Ti 4400. It's a great card, and I'm using it with an old P3 450. I get playable framerates in all the games that I want to play (Zelda, Golden Eye, Perfect Dark, SSB, etc.) So just find a brand that you like in your price range, and look at a review site such as www.tomshardware.com, and see how good it compares to the competition in it's class.
I would also suggest going with a more total upgrade than just your v-card. If you can afford the update the mobo, memory, cpu, and v-card. Which with a $500 budget, you could do really well with a AMD setup, and still have enough for a great v-card. But don't blow it all on the card, as someone said, it will really bottleneck the performance of your system.