upgrade advice for an AsRock K7S41 with Sempron 2400

[SLyK]

I recently inherited several boxes of new and used computer stuff. Included was what appears to be a new AsRock K7S41 with an equally new looking Sempron 2400 already installed. Further down in the box was an ATI 9600 AIW pro. I'd like to use all this as a cheap DVR. Would it be worth upgrading the Sempron to something else? If so, what gets me the most bang for the buck? I plan on starting with a 450 watt power supply. Will this be strong enough or should I plan on upgrading that also?

Thanks, SLyK