was planning a trip to Thailand and was going to see Vietnam as well . I heard it was beautiful there but also heard there was like 2 million land mines still in that country left over from previous wars.
I wouldn't worry about land mines. Unless you're planning on heading deep into the jungle, you have as much chance of being blown up by a land mine as you do in London.
I have seen several threads on here that have said you can live like a king in Thailand and similar places for years on only like 50 K
You hear a lot of people say stuff like that but it's a little on the bullshit side. You can live, one maybe two years on $50K unless you want to live like the locals.
And when I say live like a local I mean, 4000 baht per month apartment with no air conditioning, eating local food 3 meals a day, and not going out or doing much. But that sort of defeats the purpose of moving somewhere so you can live like a king, doesn't it?
I can't speak for Vietnam in terms of cost of living but in Thailand, in Bangkok specifically, you'll pay about $500 - $1000 for rent. I stayed in some pretty decent neighborhoods and my rent was 25,000 baht ($833 USD) per month.
Is that living like a king? Not king of any country I would want to rule

It's a decent furnished 1-bedroom, air-conditioned apartment in a nice building with a gym and swimming pool.
Yeah, in a big western city I would pay about $1200 - $1500 for the same place but surely few people in the US would consider a $1500 a month apartment living like a king.
Dr_Ngo says you can eat a local meal for $1 in Vietnam. Yeah, about the same in Thailand. Except, do you really want to eat Larb Moo every day?
If you want anything resembling a western lifestyle, you'll pay western prices. McDonald's will set you back $5 - $10 a meal.
$100 for two bottles in the hottest club in town? Yeah, same in Thailand (about 1500 baht per bottle of Johnny in a Bangkok nightclub). But, the hottest club in Bangkok isn't on par with the hottest club in New York or London or wherever.
In fact, when you start doing the math, you realize that you're paying either the same or slightly less than you might back home.
So, speaking of doing the math, $50K would be 1.5 million baht. My nut was about 100,000 a month for me and my girlfriend and we did not live some sort of superstar lifestyle at all. Sure, we ate out most nights and we went out fairly often but nothing really more than what I do back home.
So, 1.5 million over 12 months is 125,000 a month.
Apartment: 25,000
Internet: 1500
Mobile phone: 1000 (I had unlimited data plan)
Utilities: 1000
Food (300 baht per meal x 2 people) 54,000
Right there, that's 82,500 baht and I haven't even had a beer yet. That means I've got 42,500 to spend each month on entertainment or whatever. Or, roughly 10,000 per week (if I had your budget).
And, that doesn't include health insurance (if you feel you need it), transportation, clothing allowance to replace clothes as they wear out, the latest tech gadgets, holiday away from the city, etc.
So, let's say you want to live like a king on 10,000 a week . . . well, that's about 1400 per day/night. Beer will cost you 120 a bottle around most of Bangkok so 3 or 4 beers a day takes you down to about 1000 baht per day.
Sure, you can have fun on 1000 baht per day but don't plan on hitting the go-go bars and taking a girl home with you. She's gonna run you 2000 - 3000 baht for the night, plus the 600 baht barfine, plus a drink or two for her at the go-go (400 or 500 baht including your drink or two).
Obviously, I had a girlfriend so my food costs were double and you might enjoy eating local food a few times a day so your costs may vary but as you can see, $50K doesn't go as far as some people would lead you to believe. Not that you can't live on $50K, just that whole "live like a king" thing isn't quite accurate.
Instead of people saying that you can live like a king in Thailand or Vietnam or Cambodia or the Philippines, they should say that you can live there for next to nothing if you are willing to live cheap. You can live on 10,000 ($333) a month. It won't be a life of luxury by any stretch of the imagination but I think you would be hard pressed to live on $333 in any western country.
But as soon as you start mixing in any sort of western pleasures, you're really only saving about 20% - 25% over back home. So, a better way to think about it is to figure out what lifestyle you want to live.
If your aim is to live like a king then your cost of living isn't going to be radically different from back home. If this is a whole life change for you, and you're willing to live more like the locals, then it can be crazy cheap.