try sisoftware sandra, its a benchmarking software, theres a benchmark called processor arithmetic which maxes out my cpu to 100% (both cores, and ive got a e6300 overclocked to 3ghz from 1.8ghz). Theres also tool within sandra called burn in computer , only select proccessor arithmetic from that list if you want it constantly at 100% and then run it.
Ok, seriously - video editing and transcoding will eat all the cpu time you can give it. I transcode dvds to divx and the more cores the better. I belive supreme commander will use a lot of cores if you let it. Even if you dont max all cores doing one task, it is handy being able to do a cpu intensive task and play games will u wait