The question asked 1000 times!

Ill start with the question:
Basically I am wondering if I should begin playing Guild Wars, having never played it outside of beta and having no friends who play

Background:
I've been playing MMO's for over 7 years starting in DAoC and running in competitive 8v8 guilds, when that game died I of course went to WoW, eventually quit that because PvP is HORRIBLE, played EQ2/SB as well.

During my entire "MMO career" I've always played support characters and its what I love to play, in DAoC I was a Shaman and Warden, in WoW I played resto druids/priest and in eq2 I played a coercer. So basically if I were to play what type of class would best suit my playstyle, and what are some desirable classes . My entire GW experiance came from the Open Beta a couple years back so any info would be awesome

Probably Monk or Ritualist.

Monk is based on keeping the party alive through healing and/or protection.

Ritualists have some healing and protection abilities, but can also buff up their teammates.

For more information:
Monk; Guild Wars Wiki here, GuildWiki here

Ritualist; Guild Wars Wiki here, GuildWiki here

If you want serious PvE, a monk is always in demand - especially if you are good, which you should be based on your experience.
If you want to farm / solo areas, there are some pretty fun monk builds that allow you to get through parts of high end areas.

But classes like monks are pretty common to any RPG/MMO. If you want to explore different support classes, Ritualists are pretty dynamic and allow you to use spirits (follow links in post above to learn about spirits).

Paragons can be support based, but often have better synergy with one another, they can use chants and shouts to provide buffs to the party.

Necromancers have the ability to gain energy when enemies, minions, or creatures die, which makes this class very versatile and capable of using the support skills of other classes very well. Sab's team build shows the synergy of Necromancers, it is discussed here.

Another thing to consider is that you can bring 3 heroes with you in addition to henchmen. You can customize the skill bars and "flag" your heroes (there are at least 2 heroes for each profession). This may influence where you want to start playing the game (heroes are available in nightfall and in eye of the north).

I don't PvP, so I will leave those comments for others.

Regardless, good luck, and I hope you decide to try out some of the unique professions and enjoy all that the GW series has to offer.

You can start playing even if you have no friends playing GW. Most of the people are friendly and you can join a guild, so normally that shouldn't be a big problem.

You should start playing a Monk, pretty simple, but it gets a little harder the more you advance trough the game.
A necro is a good choice too ^^. They can put some evil hex, steal life and make a minion army.

If you are going to buy GW I say start with :
-Nightfall since it gives you access to heroes, then
-Prophecies, for me it has the best story and then
-Factions, AB is one of the best thing ever !.
-You can buy EotN as it gives you access to heroes too, but since it's an expansion, you'll need one of the above three.

Here's some useful links :
http://wiki.guildwars.com/wiki/Main_Page
http://gw.gamewikis.org/wiki/Main_Page

I would add elementalist to the list of ideas.

They can be an excellent support class as well as having great offensive skills and you also get the greatest energy pool for skills.

I was thinking Monk or ritualist secondary for support mode and later changing secondary to try out other builds.

Never be afraid to test out all of the proffessions in GW, they are not quite like any other game.

In GW you can make multiple chars, so go ahead and start a monk/rit/ele/paragon, but dont be affraid to step into the other classes. A warrior can be a lot of fun to play as can the Ranger and the Necromancer.

There is no penalty for trying them all, its easy to delete and create a new char and you will know soon enough wheather that class is fun to play.