I think machead3 is a bit confused by the ranges you've mentioned. the title says its a 24" iMac with a GeForce 7300 GT graphics chip, whereas the range selected was the iMac G5, which is completely different, and have very different common problems.
The iMac G5 is the one that has capacitor issues, and can create a graphics fault, were as the 24" range had problems with both its power supply, and its graphics chip. can you confirm the symptoms you are having with the machine? as if it is video related, it could still be the the logic board, LVDS cable or the LCD panel...
But with regards to your graphics card, there is 1 of 2 solutions available. you can either re-flow the board, which is a fairly complicated procedure and will not be a great long term solution, or you can purchase a replacement card, but they are very difficult to come by, as that range has been classed as vintage for a while now.
sorry, neither is a great solution, i know.