Belt Tensioner?!

[V_Dub_Wagon]

03 Passat GLX wagon w/ v6 105k miles..... now that that's outta the way. I was hearing a noise comin from the engine compartment while I warmed up the car. Can't really describe it other than it sounded like the fan, or belt. Then, while a few blocks from home... heard a sound, and lost the power steering, battery light came on and I got the clear-as-mud message of "Alternator Workshop". After some investigating on this end, figured it was the belt that crapped out on me, and when I looked back in the engine, turned out it was the belt. But it didn't break, I attached pics of the item in question. It looks like it might be the tensioner, but I'm not entirely sure. I got myself a Haynes manual and feel fairly comfortable in doing the work myself.
Here's the question... I haven't been able to find a good image in the manual of what the thing might be. To anyone with experience, how difficult is this to get to? I don't think my water pump's been replaced, so I'm planning on doing that too... is there anything else I should do while I'm in there? And I've got the basic tools, is there anything else I'm gonna need?

Thanks in advance...

[V_Dub_Wagon]

Well, I did it... sadly, without the help from anyone here, as much as it would have been appreciated. FYI... it was the tensioner... I had to put the radiator in the "service position" which is basically where you remove the bumper, put some long bolts in the bumper and you can slide the front end like 4-5 inches forward w/o disconnecting the radiator. I bought a Haynes manual, and it was fairly accurate, and the work wasn't as hard as I thought it was going to be. It didn't mention that I needed to disconnect the turning signals or fog lights, but I figured that out. Also, the pull tab for the front hood latch is kinda tricky, so I just left the grill dangling on that thing. I found a Dayco tensioner at Advanced Auto,in stock, for $54. I live in the Chicago area, and its cold, so I left the water pump for the springtime when it warms up. My baby can use a coolant flush as well as some other things, so I'll tackle it all when I'm not freezing my ass off.
I see some folks took a gander at this post, but didn't comment... if anyone has any questions.. lemme know