I'm looking to procure a PC for the express purpose of displaying video content from a Synology Surveillance Station. This PC just needs to run Windows and have enough horsepower to play back several 640x480 feeds at ~10FPS at one time.

What should I aim for? Should I be looking at a faster CPU or better graphics? I thought about purchasing a used Core i3 Optiplex and throwing an inexpensive mid-level graphics card in there.

What do you folks think?