Okay, I'm upgrading my graphics card and need to know whether the ones I've picked out will work with the rest of my comp and whether I'd need to buy a new power supply for any of them.

GeForce 9400 GT
Radeon HD 4830
Radeon 4770

My current setup is:
Acer Veriton M646
Intel Core 2 Duo CPU E4700 @ 2.60GHz
3GB DDR2 RAM
NVIDIA GeForce 7050 / NVIDIA nForce 630i
Windows Vista 32 bit OS
250 Watts Power Supply (I think, is there a way to check without opening it up?)

 

Are you sure that your SMPS is 250W, cause ususally they are 400W or 450W, especially considering your configuration.

I am not much familiar with ATI's cards. However, the GeForce 9400GT works fine with a 400W SMPS, it should even work with a 250W one(not sure though).

You could check the requirements for the cards, its ususally mentioned.

My advice would be to check the GeForce 9500GT, the price between 94 and 95 is not that much and the later gives much better performance and runs fine with a 450W SMPS.

Hope this helps.

 

You might need a new PSU before thinking about a graphics card.

 

The wattage is usually clearly labeled on the box, otherwise steel yourself for hardcore googling any numbers you can find.

 

PSU wattage is usually on the PSU itself. Mostly on the side. Depending on your tower you might have to actually remove the PSU to check the wattage. also 250 watts?
I think I have a 300/400 and I only have a Core 2 Duo with an 8600 Geforce.