One of the biggest strategy games returns in MMO format
In the World of WarCraft, you can play amongst two different factions, the Alliance and the Horde. The initial game limits you to the standard races, getting the Burning Crusade gives you access to two new races, the Blood Elves and the Draenei. Each faction has it's advantages, one may notice that the Horde is extremely dominant in PVP mode, however you are limited in class selection as no race has access to the Paladin class, whereas the Alliance has human and dwarf paladin's, only the Blood Elves can use the paladin class. Each race has it's own advantages, Tauren's are slower but can take a beating whereas the Undead are smaller, faster but are a little bit more frail in physical combat, regardless of the class choice. If you like to agitate people in PVP, Gnome rogues tend to be a popular choice since they are small and hard to hit since they can move quickly.
You can choose from being a pet loving hunter, a transforming druid, a magic weilding shaman or mage, shadow magic based warlocks and their minion, the stealthy rogues, holy magic weilding preists and paladin's or the all brute strength of the warrior as your classes, the upcoming expansion The Wrath of the Lich King will offer a new class to those level 55 and above, the Death Knight. One thing new comers to WoW will experience is getting familiar with each class and understanding how to build your character properly to be successful, plus which ones suit your combat preference.
As you level up your character beyond level 10, you will earn 1 talent point per level and using them gives you special fields of skills, however since you are limited in how many talent points you get before you hit the level cap of 70 (soon to be 80), you should research your character build beforehand. For me I wanted to be a paladin and play PVP a lot, however the Alliance does not do well on the PVP battlegrounds most of the time, so I had to wait to get Burning Crusade before choosing to use a paladin, at which point I opted to be a Protection based paladin which goes along with the secondary skill of Armorsmithing which you will learn after mastering Blacksmithing. The focus of a protection paladin is to have the best armor, sheild and single handed sword, a retribution based paladin would be more focused on brute strength and speed over defensive abilities whereas a holy paladin is magic based for healing, however mana growth is low compared to a preist so it is better not to go down that road.
The variety of weapons, armor, items professions and skills will really blow your mind. There have literally got to be millions of items in the game, polearms, swords, guns, daggers, axes, maces, wands and staves as well as companions, mounts and things such as potions and little items will make for interesting times.
However with all that WoW has to offer, you may find this game will take some time to get into, but if you do get into it, you will find yourself always wanting to play.