Is the LNB the "L" shaped piece that's pointed back at the center of the dish, or is it referring to the coax terminals? I'm confused as to what the difference is between a dual LNB and a twin LNB. Can someone clarify this? I have a Dish 500 system with 2 of those "L" shaped pieces on the same satellite dish, but each only has 1 coax terminal, as opposed to each having 2. So, would this be a dual LNB or Twin LNB?

On my Direct TV setup it is dual LNB (low-noise blocking) converter
outputs for connection of multiple room receivers. Each has its own output for the ability to connect to two different receivers.

You have a dual. The LNB is the actual signal receiver at the end of the "L" shaped bracket. Each of your coax connectors can go to a different receiver.

Are you sure I just don't have a Twin? My Dish 500 dish has 2 of the "L" shaped pieces, but each of those pieces only have 1 coax connector. My other satellite dish for the 61.5º bird only has 1 "L" shaped piece, and it also just has 1 coax terminal.

Yes you have a twin. I have the Dish 500 too, and I have a dual twin LNB. That is 4 coax connectors (2 in each LNB). Each pair of connectors is a 'twin LNB and two of these twin LNBs makes it a 'dual twin LNB.'

Oh, I didn't even know there was a difference between twin and dual. I just knew you had two LNBs, each having an output, and didn't know what that configuration was called (I've only had a single, or is it called a half-twin?).

LNB: that part at the end of the arm that reads the satellite signal and sends it to your receiver.

Dual LNB: One LNB that can read the satellite signal and split it out to two different receivers. These signals are from one satellite. I say "can" because you don't have to have two lines, you can use this as a single LNB and add a second line in the future if you want. If you have one LNB with two coax outs, you have a twin. If you have a single coax out, you don't have a twin.

Twin LNB: There are physically two separate LNBs at the end of the arm, each sending a signal from a different satellite.

Dual Twin LNB: You have two lines from each of two LNBs, so you have four lines. Note that you can use divergers and convergers so that you don't phsyically have four lines running across your roof and in to your house, but behind the receiver and next to the satellite, you'd have four lines.

As huzefa said, you have a standard twin LNB.

Note that some people used to DirectTV use the wrong terminology (when I just had my system set up, the place I ordered it from kept calling it a dual LNB when it is actually a twin LNB, I'd correct him and he'd look suprised that anybody would actually know the difference).

I need to correct you all here! You are using the word TWIN improperly here. A TWIN LNBF is a single unit LNBF that is double wide (that contains two Dual LNBF's and a SW42 switch built into a single housing) which is used on DISH 500 dishes only. What Patrick seems to have are two Single LNBF's NOT a TWIN LNBF as he describes it as "I have a Dish 500 system with 2 of those "L" shaped pieces on the same satellite dish, but each only has 1 coax terminal". Their is no such thing as a Dual TWIN LNBF you have either a Single LNBF, Dual LNBF, TWIN LNBF or QUAD LNBF. On a DISH 500 dish you would have either two Single or Dual LNBF's or one TWIN or QUAD LNBF. A DISH 500 will have a Y-Adapter at the end of the LNBF arm that accomadates two DUAL/Single LNBF's or a Single TWIN/QUAD LNBF.

I am surprised you have two Single LNBF's on your Dish 500 because if the DISH 500 dish came with the receiver it would come with either a TWIN LNBF or two Dual LNBF's. If you got a DISH 500 upgrade from Dish or a local dealer they should have (if you had a Single LNBF on your Dish 300) replaced it with a Dual LNBF and added a second one that comes with the DISH 500 Upgrade. If you had a Dual LNBF on your old DISH 300 dish then someone has ripped you off by putting two Single LNBF's. I should know as I am a DISH dealer and that is how it is supposed to be handled!

Single LNBF = One LNBF with a single Coaxial Output
Dual LNBF = One LNBF with two Coaxial Outputs
TWIN LNBF = One Double Wide (contains two Dual LNBF's and a SW42 switch built into a single housing) with two Coaxial Ouputs
QUAD LNBF = One Double Wide (contains two Dual LNBF's and a SW44 switch built into a single housing) with four Coaxial Outputs

We live in a duplex, and the couple that share it with us are getting into home theater. He just bought a 65" Mitsu HDTV and asked for my advice for getting hooked up with either Dish Network or DirecTV. I have the Dish 6000 and 2 dishes for pulling in both the SD and HD programming from all 3 birds. My question is, is there any way I can share my hardware with my neighbor if he buys the Dish 6000 reciever, without degrading my signal quality? If so, what would he/I need to do this?

What's the best way to get him hooked up with programming then?

I have one of those certificates good for free equipment and installation. Should I have him use that? Or should I just have him call a local installer to come out and add whatever is necessary to my hardware to get him up and running? My neighbor is going to buy is 6000 receiver online, but I'm not sure what the least expensive way is to get him up and running. If he has a local installer come out, can he still use that certificate? How should we go about this?

I don't think you would lose any signal quality if you have a line from both ur dishes to his new 6000 receiver. I'm assuming you have some coax connectors open on your dishes. If you don't, then I'd suggest using a SW64 switch and then connecting his receiver to that switch. The signal loss would be minimal using the switch IMO; I only have experience with a SW21 switch.