"I occasionally use the top and uptime tools to see what my current server load/cpu usage is. However, I would like a tool that shows me a history of the load time/cpu usage. This might allow me to determine when (if) my system is bogged down."
You can do a crude job of this with top. Try something like:
top -d 60 > /root/top.txt
To append to an existing file:
top -d 60 >> /root/top.txt
Be prepared. Create a LifeBoat CD.