hm. if you're using a decade-old computer, then the chances are it won't be able to handle uncompressed renders at dvd quality... for my short-film projects, i render everything uncompressed at 1024x576, which is the correct format for PAL widescreen (can't comment on NTSC frame size really, although i did think it was a bit bigger than 852x480), but i can get away with that because i've got a shiny new machine with a quad-core processor and 500 GB of hard disk space. if you were using a higher-spec machine, then i'd advise you to do the same, but if it's 10 years old, then it'd probably take one look at the massive file sizes (i had a 32-second clip that was over a GB once), curl up into a little ball, and die with a pathetic whimper...
personally, i like the microsoft mpeg-4 codec, it always worked fine for me, irrespective of aspect ratio, but i still use uncompressed for major projects, just to get that extra level of image quality.
- colclough