A few things Blarg forgot to mention about XP. We aren't currently running an XP system based on the creatures overcome. We have taken and adapted the XP system that Wulf Ratbane's group uses, where you gain XP on your contribution to the game. We have set it up so that everybody gets about the same XP, give or take depending on how much they help each other.
I can see Thanee's point about the 3.5 XP system but we want our characters to level slower than the base system, I also believe in rewarding characters for thier actions (reinforcing the good, the bad usually is taken care of by character death...). I might sit down with Blarg and rework the XP system again, my attempt is to bring everybody to about the same lvl +/- 1lvl. But, the main thing is that when they are all the same lvl I would like them to be of approx. equal power.