Bicycle Mechanics - trying to understand bottom brackets

The last time I was really into mtb's all you had was a square tapered bb..

whats the difference/benifits of a spline drive bb and whats called a x pipe?

what different types of bottom brackets are there?

my bike orignally used a 73mm english 113mm length bb..

if I wanted to upgrade my base model cranks to something like this..
only the ones i saw are in silver and called the Ride XC, but have the same overall look.
http://xoomgear.com/i/p/l/CRNK-9.jpg

I suppose the spline drive or octalink is what I'm looking for?

whats this outside bearing stuff I see listed all about?
lots of questions, eh? :D

I ask these because i couldn't find what I was looking for here on on the rest of the net.

heck, if you know of a site that can break it down n00b style, forward it onto here please.
thanks

Octalink is a Shimano invention. Appearantly the other crank manufacturers didn't want to pay royalties to Shimano so they agreed on their own Isis spline pattern. That's what the crank in your picture has. You can't mix and match Octalink and Isis and, in fact, there are actually two different Octalink spline patterns that can't be intermixed.

While I've personally been satisfied with the performance of Octlink bottom brackets, manufacturers found a problem. The big hollow spindles didn't leave room for very big bearings. Their solution was to move the bearings out beyond the bottom bracket shell. The exo-bearing bottom brackets have to be paired with cranksets in which the spindle is swedged onto the right crankarm.

Yep, basically if you match the BB length and style to the crank and your frame design, they all go spinny-spinny, the derailleur goes shifty-shifty, and you go ridey-ridey.