High Load Average

I am sorry, I know this a completely noob question, but I really need some help.

The first week of February, I ran an "emerge -u world" on my Gentoo based linode. Several things broke at that time, basically apache and smtp. After several days, I got things running again, but I have never been able to figure out why my Processor Load Average is high.

You can look at this Larrd Graph and clearly see that my linode is reporting High Load Average since February

So my question is how do I track down the rogue processes?

Thanks,

Darley