I would put it this way, unless there is a specific reason that you need to use Mpeg4-ASP, you should use Mpeg4-AVC. Brother John listed all of the major reasons you might need ASP (and a bit extra), and If they don't apply to you, then ASP is, as far as you are concerned, obsolete.

Lots of people are more familiar with divx, and hardware demands are a lot less - yes, there is gpu acceleration, but that's still problematic for a lot of people. That's about it though. AVC is simply superior otherwise.

Guys here forget something, just few people have h264 hardware decoding ... Xvid/Divx run on slow computer, this is what it's not obsolete atm AVC > Divx / Xvid quality but not for decoding yet.

the only reason (i can think of) to still use xvid/divx is widespread hardware players support.

options for gpu decoding have gotten cheaper .. assuming you have a mobo that can do pciexpress.... and have the money. its worth it. im using my video chipset. 720p x264 is all it can muster smoothly.. 960x1080 works with lots of jitter

I have found that DivX that is encoded with 25% higher bitrate is equal in quality to X264. I believe this website which did a double-blind test supports that. Since DivX/XviD seems to play everywhere it is worth larger filesizes for me. I find X264 lack of standards to be frustrating. Just because you encode a file in H264 does not mean it will play everywhere you think it should. For example I encoded (on my PC, in H264) one movie this weekend 8 different ways; only one of the encodes would play on Quicktime on my Mac (nero digital). If you really want to ruin a weekend try to make a H264 movie on your PC that will play on a Apple TV. If you want to make a movie on your PC, keep it on your PC, and play on your PC then you might want to use H264; else use DivX...IMHO.