OSS is the older Linux sound system, and is on a usage decline at the moment.
Mind that there are currently two branches. Oss 3.x is the in-kernel Oss stuff, which is effectively being deprecated. Oss 4.x is being developed outside the kernel tree and it has actually some good things about it, though it isn't admittedly as broadly used as ALSA is nowadays.
ALSA is the current standard, and seems to work pretty much universally. I have the same nvidia high def mcp51 setup as you do in the other thread, and remember having to wait until drivers arrived in order to get sound on a MSI AMD64 mobo I have at home. And by the way it runs alsa fine. Maybe your laptop has special needs.
ALSA is -by no means- the panacea. It works for most people, but it does some nasty things. As an example, if you have an audigy you will suffer from the fact that dmix doesn't work with surround, which means that you can't hear anything else if you are playing something through the surround filter. So you are limited either to stereo or a single sound at a time. It also lacks a true master channel which means you have to go sliding three controsl each time you need to regulate your volume. I work around this with a bit of shell scripting to set all of them to the same value with a keybinding, but it's quite annoying.
However this seems to affect only some models, not all the audigy's, but a number of people have reported this same problem. I don't know if it happens for other cards.
The sound is not the cleanest either.
I hadn't any of these problems with Oss4, but it didn't had any -functional- support for midi, and most proffesional audio apps just don't work with oss4. Gkrellm and most wm* dockapps do not work -at least not correctly- either with oss4, which is a pity.
PULSEAUDIO seems to be the future, when the bugs are finally ironed out. From what I read, many are still having problems with pulseaudio and are reverting to alsa to get their sound working.
Pulseaudio is just an high-level sound server, you still need either ALSA or OSS to get sound. Pulseaudio is not a driver, you still need either of these to get pulseaudio working, which just adds another level of complexitly and another source for bugs, problems and annoyances. I am not saying that pulsaudio is useless but most users really don't need yet another layer to do what alsa and oss4 can do natively (or should do natively if they weren't as buggy as they are).
So, to sum up and answer the topic at hand. I usually would live much better with oss 4.x (not 3.x), but only if you don't need midi, if the apps you need to run can run with oss4, and if your card is supported. If one of these conditions fail, you have no option but to use ALSA.