I don't think there will be a performance problem just because it is an older graphics card, it is designed to handle NTSC video and that is what you are trying to capture. It should do just fine. Perhaps trying to capture a larger, non-standard video type might be a problem with an older card. Findng current drivers (for Windows XP) however may be an issue. Check the ATI site...
What could cause problems with the video conversion is the speed of the host system, in other words your CPU/hard disk and possibly the slot for the video card. The analog video data is recieved by the ATI RAGE FURY PRO, stored in on-board graphics memory, the on-board DAC chip converts the analog video to digital (the RAGE FURY PRO has a 300 MHz DAC), the video is then transfered over the AGP slot to the system memory and then written onto your hard drive.
What causes dropped frames or out-of-sync audio/video is when the CPU or hard drive is not fast enough to keep up with the video, for example if the hard drive is fragmented, or the CPU or HDD is busy performing another task. Just ensure that no other programs are running while you are capturing the video (check for programs running in the background like an anti-virus program) and that the disk space you are capturing to is (ideally) a separate, defragmented hard disk or partition.
If you are capturing a long segment of video (several hours), to be safe, you might want to break up the capture, stop the video tape at an appropriate point, save the video file, then start a new capture. You will be able to edit (join) these seperate file slater in Adobe Premiere.