actually, you can travel directly, without changing buses, from cambodia or ho chi ming city. in cambodia there is a bus co. close the central market.
in saigon the bus office is in "distirct 1", across a very long park, about 2 blocks away from "orient hotel".the trip takes about six hours including time spend at the crossing border. my last trip along that road was last july 2005. on the cambodian side i was told the visa was $25, i handed them $20 and walked away. from cambodia to thailad you either go through ko kong, you would have to take a boat from sihanousville. i find this trip unconfortable, i travelled this route a couple of times, or you can take a bus from phnom penh to poipet. i have read that on this route the road is paved.
[quote=ekspat]i've done it from saigon to pp. first part by minibus to the viet/cambo border, worked out well and fast on a reasonable road, then you've to change vehicle since the viet doesn't enter cambodia.
waiting for the immigration in vietnam/cambodia can take some time because they want to sell all foreigners "special treatment" for a few bucks. that means, what they have to do anyway, it's just faster by jumping the q, what might be okay, since you'll wait in the burning sun. or in rain.
on cambo side it will be rougher, the road and in general. there might be the bus missing, or broken down, slippery muddy road when raining etc. i had to wait there 2 hrs or so for the bus.
my bus ride was quite scary in the first part then, because the driver was heavily tired and felt almost asleep behind the steering wheel, i could see it in the mirror.
later after crossing a lake (or river) by ferry then the road became extremely bad with potholes, that the average speed was down to around 30km/h or so. fine with me, because the driver now had alot to do to drive around these potholes, so no way for him to sleep.
arrived in pp after 12hrs for a short 230km-journey, 3 out of this 12hrs in vietnam. and i think there isn't much mongering on the way. i won't do it again.
i haven't done it so far from pp to thailand, can't help.
cheers![/quote]