[quote name='georox']Just buy Diablo 2, since all Guild Wars is, is a very glorified Diablo 2.[/QUOTE]
While I still avidly play both, I think Guild Wars has the edge thanks to its unique item system and extremely balanced and varied PvP modes. However, if you don't like the idea of items not being varied, that may bug you about Guild Wars, but I much prefer a system that places pretty much all favor on the more skilled players rather than those with the "best" items.
It is very easy to make a "max" character so you can get straight to the high end content which the majority of the game in Guild Wars.
The other great thing about Guild Wars is the encouragement to constantly reroll your character to fit a situation. You can change your skills, attributes, and secondary class freely in towns to prepare for specific enemies in upcoming areas with no penalties such as refund points or an NPC that charges you money. It is all free and easy.
Both have a defined story and end which is one of my personal favorite things about both games. I hate open ended MMO's with a couple of main quests in place of a story.
Either way you can't go wrong with D2 or Guild Wars if you can get past D2's graphics and resolution.