I'm using Microsoft's Performance Monitor to dump logs of RAM, CPU, network, and disk usage from multiple servers. I'd like to get a single metric that captures the state of a given variable to a good extent. For instance, disk usage is pretty stable, so if I take a single reading that says I have 50% remaining disk space, that reading will give me an accurate measure for the day. (The servers aren't doing heavy IO writing.)

However, the tricky part here is monitoring CPU and network usage. The logs currently dump the % CPU usage every ten seconds. If I take a straight average of the numbers, it may not represent reality, as % CPU will be much lower during the night than day. (We host websites that sell appliance items.) I'd like to get an average over a span during peak hours (about 5 hours in the day) and present a daily peak hour metric. Of course, there are most likely some readings that will come in as overly spiked (if multiple users pinged the server at once) or no use (a momentary idle state). Is there a standard distribution/test industries use in these situation?