I don't know if fraps can render without sucking up system resources. Fraps dumps all of the data to uncompressed video/audio, which are huge in file weight. i.e. about 6 seconds of video would take up about 30mb. Be sure to have a huge amount of space on your hard drive, and be prepared to be annoyed by the choppiness of the game you are playing. I believe there are other screen capture tools that might render to mpeg quickly without dropped frames. However, if you want pure lossless capature, just go with fraps and uncompression.