After spending an extra day in Phnom Penh to get over my dodgy stomach (granola and salad sorted me out), I ventured into Vietnam.
There are several options for crossing the land borders, including minivans and an assortment of buses. I went for the Mekong Express, which I found to be very good. It cost US$14 through my hostel Phnom Penh to Ho Chi Minh City (Saigon), and took eight hours including border procedures.
They did mess up my booking and had me down as going back to Siem Reap, but thankfully they had a spare seat at the back.
I'd heard stories of a lot of corruption at Cambodian land borders, but going out I had no problem. I did see a guy sitting near me slip the officer who took our passports at the start of the journey a $1 note, and surprise surprise his name was the first to be called when we arrived at the border gate.
My passport was also the very last to be called on the Vietnam side, and I was concerned they'd ask me to pay for them to "find it". But my faith in humanity stood up and it all went smoothly.
A few hours later we pulled into Saigon (it's quicker for me to write the old name Saigon than Ho Chi Minh City, but don't call it Saigon in the north of Vietnam - apparently that can cause offence. People have long memories).
And my first taste of Vietnam was to follow.