Train from Bangkok to Luang Prabang

No trains into Laos from Thailand or anywhere else. Train from Bangkok to Nong Khai near the Friendship bridge.From there you can cross border into Laos then get a tuk tuk into Vientiane. Look online for info. Try thailand tourism sites. 

You cannot get business visa at border. You can only come in on a one month tourist visa, single entry, cost between $30 and $40 depoending on what country you come from. Need passport photo for the visa form.

thank you Stumpy, well I guess that's it. Have you tried taking the train?

No never tried it.
All my travel is from Bangkok to Vientiane by air. Paid for by my clients but not expensive and only takes an hour. Cheapest is with Lao Aviation. Thai Airways also fly in and out.

Flying means there is not too long a wait at immigrationin Wattay airport. You get the visa paperwork on the plane and only need to photo and US$$$.

There is often a long wait when coming into Laos from Nong Khai. You will need the name of a hotel with a phone number to put in the visa form. This is just a formality that needs doing but they never contact the hotel. 

Airport close to town, only 10 minute trip.

i have used the train many times. Two leave Bangkok between 6pm and 9pm. Sleeper cars are available for about 700 baht first class, reclining sleeper in 2nd class a little cheaper, and third class are hardwood benches that do not recline and is very crowded. The trip usually takes about 12 hours. You buy your ticket at the train station. I would go early as tickets can be sold out. (If you are coming around Sang Kran better to fly. Tickets will be sold out a week in advance.) Sometimes it will side track and wait for another train to pass. I have seen it delayed as much as 8 hours but that is highly unusual. When ever I used the sleeper I was awake by 6 am and before Udon Thani so I had another two hours to check out the view (not much).
When you get to the train station in Nong Khai station things are a little more hectic now. It used to be sedate but the husslers and visa pushers are not rampant where before the did not exist. You will take a tuk tuk to the bridge, tell them you have a visa already if they stop at a place just don't get off. Tell them Mai Oww, Mee visa dio nee. (I don't want. I have visa now) The cost is too high but about 50 baht which is what it cost from downtown to the bridge. It used to be 30 baht.
When you get to the immigration you will pass the thai side easily. Just to the right as you exit the booth is a ticket stand for the bus across the bridge it is either 10 or twenty baht. But not bad at all. Then you to the end of the area towards the bridge and you will see some people waiting for the bus. Just give them you ticket and get on. It is usually crowded unless it is around 6 in the morning.
When you get off the bus in Lao you will be right at the immigration stand. On the left is a currency exchange that may or may not be open. Ahead and beside it you will see two windows. Go to the window on the left and they will give you the forms. Fill out the forms and go back to the same window. Be sure you have a picture and your money. Have US cash $35 US if possible. If not they will charge 1500 baht and you pay an extra 350 baht in the rate exchange more than if you have dollars.
When you give them your passport and forms go around to the end of the office and stand by the window on the right side (window 3) When they put in the visa they will hold your passport out the window and they may or may not call your name. Now you just go through all the immigration booths don't stop and go to the end of the area to a person that sits at a table and checks the stamps you are now in Lao.
For transportation again, negociate but it can be higher than it should be. I am used to the deal so I go across the street to a white and grey bus into Vientiane to the Morning Market Talat Sao. It cost 6,000 kip not sure about baht. Maybe 20. It goes straight to the morning market unless you say to let you off earlier. Again, it can be crowded I usually luck out and get a seat. The other way is to find one of the many carriers there.

If you don't fly into Vientiane you can fly into Udon Thani and go to the bus station there where they have a bus into Vientiane. Not sure of how to go about it, I just know they have it.
Hope this helps.

T-Lao I'd find my way with that info. thank you. I may be taking fastest mode though, but still checking better connection may be Cambodia or Bangkok or Singapore. But I'd surely try train to Laos as one of my travel plans next time.

hola amigos, soy de Ecuador pero tengo la nacionalidad española, me gustraia conocer gente que viva en Noruega,y me eche un cable con un trabajo, estoy desesperada...
Un saludo.