(Jan 2003) In response to questions I received about my trip, I have posted additional information below. Thanks to all with their questions and comments.

My Schedule:

First day, I started at about noon and stopped at 6-6:30 pm to set up camp. [It became dark around 7:30-8 pm, if I remember correctly.]
Second day, I started at 9-9:30 am and stopped at 7-7:30 pm and stayed with a fisherman's family on the river bank.
Third day, I started at around 9:30-10 am and stopped at 6-7 pm to set up camp. [On these two days, I took a 30-45 minute lunch break and a few 10-20 minute rest stops in the afternoon.]
4th day, I started at 9-9:30 am, took a 2 hr lunch stop in a small town, and stopped at 7-7:30 pm and stayed at a fisherman's home on the river bank.
5th day, I started at 9:30-10 am, took a 1.5-2 hr rest stop in a small village, and stopped at around 5 pm in the Thai town of Chiang Khan.
6th day, I started at 8:30-9 am, took a 45 minute lunch break plus some afternoon short rests, and stopped at around 6 pm in a Thai village.
7th day, I started at 9:30-10 am. I don't recall taking any long breaks that day since I was aiming to reach Vientiane on the same day. Arrived in Vientiane around 4-5 pm.
The water flows fairly swiftly on that stretch of the Mekong (certainly much swifter than the heavily dammed Danube), so one can move fairly fast.

Equipment:

I used a Nautiraid folding kayak (Alu-14) of 14 feet length with 28" beam and 14" depth, along with a two-piece Epic fiber-glass paddle of weight 1lb-11oz, which was very comfortable to paddle with. [I did not use a carbon-fiber paddle as I was informed that it's more fragile. This may change with better technology.] I wore a low profile PFD (a Stohlquist Wedge) which, when the shoulder straps were undone and put to one side, allowed my upper torso and arms to move freely without chafing against anything. It also allowed for better cooling of the upper body. Other items: repair kit, duct tape, floatation bag, head lamp, bivy sac.

Camping:

I brought for camping a Goretex 1-person bivy sac made by Outdoor Research, and one plastic ground sheet. (Since it's humid and hot during the summer, it's best to get one that ventilates well.) Rain is not uncommon. I didn't bring a sleeping pad to save volume, but it would be good to bring one, such as Therm-a-Rest ProLite, which is lightweight and packs small. In June, the low water level exposed sandbars on which camping is possible. During high water level, one likely needs to clear some bushes. Bathing is a problem as the muddy Mekong water is not terribly inviting for this purpose. Clean water is available in villages, but one may need to paddle for another hour or two to reach one. If no village is nearby, a local family might be willing to offer lodging. The family I stayed with on the second night had a nearby spring for bathing. After two days without a bath, it was sheer heaven.

Health:

There were villages or small towns every 30-40 km at which one can buy bottled drinks. There were even some floating grocery stores where I could buy water and food while still in my kayak. Of course, the situation may be different in other less inhabited stretches of the river. I brought a water filter and iodine tablets (as well as medicine for diarrhea), just in case, but I did not use them. I did suffer an upset stomach after eating the breakfast prepared by a fisherman on the 4th day.
The sun and heat was a bit of a factor, especially in the afternoon. Even though I used an SPF 45 sunblock and often wore a hat (though not always), I had the worst sunburn on my back, shoulder, and arms (compared to on other long-distance bicycle and kayaking trips I had made), which became infected upon my return to Seattle. This could be due to the specialized anti-malaria drug that I was taking, which can make the skin sun-sensitive. [The special strain of malaria in the Mekong area is apparently resistant to the more conventional anti-malaria drugs such as Chloroquin.] On the other hand, the heat made it extremely uncomfortable to wear a layer of protective clothing. I recommend bringing good sun protection and anti-biotics. Oh, bring insect repellent too.

Navigation:

In June, the low water exposed rocks and I once encountered large whirlpools (about the length of my kayak in radius). Another time my kayak was caught in a strong current directing it on a collision course with a pile of rocks (the pile has a gap in the middle into which the water was funneled). But the water flow slowed just enough as I approached the pile that I was able to paddle around it. It was a close call. This may not be a problem if one paddles when the water level is higher.
I had difficulty finding a good map for the Mekong region. I used the Laos/Thailand map published by Lonely Planet, which was the best I could find in Seattle. The map is not very detailed and the town names are written in English, which was not very useful when the signs in a town/village are in Lao only.

A book that I found useful for my planning is

The River's Tale: A Year on the Mekong, by Edward A. Gargan
The author spent a year traveling (by autos and boats) along the Mekong, starting in Tibet. It gives useful information about the people and places along the way.

Overall, the trip was a great experience for me and I hope to return some day to explore other parts of the river.

Paul