Just another vote for TMPGenc and Nero for burning (or even Roxio . . . even though most ppl here hate it.)
I converted all mine on a Celeron 600@900 with 256MB RAM. It's not very fast (converts about 1.5hrs of DIVX video into SVCD format in about 4-5 hours if I remember correctly) but since it's just a spare box and not my primary system it doesn't bother me with the wait.
However, I personally gave up on converting downloaded DIVX files into SVCD awhile back since it's not really worth the hassle. While I never really had any audio sync problems, the video quality, while good, was still noticeably weaker and noisier than DVD (and sometimes even broadcast) once you got it converted and on your TV screen. It also depends too much on the source DIVX rip or video quality too. This is all just assuming you're doing what the majority of people do (download DIVX rips online and then convert them to SVCD for viewing in your DVD player.) I still download DIVX movies to watch while I'm working at the office, but don't mess with them for TV viewing anymore since I just buy stuff I want for long term.
I do think SVCD would be VERY useful for converting digital home movies to DVD-player compatible format though. I've seen examples of SVCD quality from these and those look VERY nice. Unfortunately, I don't have a digital camcorder

Then again, I don't really need one.