Engilbrand said:
The total XP after 10 should level you. Think about the other major thing that they've said, though. XP is not a resource. Nothing will ever drop it. That means that you don't even need to keep track of XP. You can just periodically level your players if you decide that it's time.
I think counting XP is important because levelling is important in D&D. Therefore, the things for which you are rewarded --in XP -- are things that are important. Take it one step further and the things for which you get XP are things that the DM wants you to do. XP is a carrot to get a certain playstyl;e response.
Let's look at the various editions as baselines:
1E is largely about combat and exploration and the search for loot. Therefore, it makes perfect sense that you get XP for both overcoming creatures and for the treasure you find, and that rarer, more powerful creatures tended to have more treasure. You also had the interesting effect of getting XP for the items to found, but you could get more XP -- via gold -- by selling it off.
2E started the trend toward railroading storytelling adventure paths, and took itself much more seriously as a Role-Playing game than 1E did. Not surprisingly, 2E focused extra XP awards on correct, narrow behaviors that made sure the players stayed within their stereotypes and niches. In addition, 2E made the "story award" more explicit, made monsters worth more and (IIRC) took out the gold=XP element.
3E awards XP for one thing and one things only: winning. As long as the PCs win, it doesn't matter whethger they kill their enemies, trick them or even sidestep them. This makes sense given the tendency of the system to reward optimal builds -- the XP reward system promotes optimal play.
Taking out the XP system entirely means that there is no built in method of promoting a playstyle. The players know you will just be levelling them when you get bored every other session or so. I am currently running a game that way -- the MWP DragonLance modules do this -- and I hate it. The only way for the PCs not to gain a level is for the game to end, because they only gain a level upon successful completion of each chapter. It has the benefit of not requiring the players to hunt down every last draconian or goblin as they flee a battle, but it also doesn't push them to do anything outside the linear adventure path.
Gaining XP in small doses, working toward the next level, is, IME and IMO, one of the great selling points of D&D. Arbitreary advancement and rapid advancement undermine that part of the game and make the whole thing, and play in general, weaker.