I don't know about it taking 12 hours, I could usually convert 2 movies a night while I was sleeping if I queued them up, so 3-4 hours a piece. The long tutorials on doom9 and videohelp seem to be aimed at people who are looking for the best possible conversion for the space...generally audio & videophiles, hence the complicated set up and customizing settings for every single movie. They're probably tweaking a lot of things and running several encoding passes per film, which will take substantially longer. Using AutoGK, the video quality is great, if maybe not quite as great as they would demand. I'd set two or three (if I was sleeping in) up right before I logged off for the night and was able to get nearly 40 of my movies done in 2-3 weeks with barely any effort (The actual ripping of the DVDs only takes a couple minutes, then you just set AutoGK up to process the queue and you're done, with two freshly compressed movies waiting for you in the 'morn).
This was on a fairly slow PC several years ago, as well. I suggest giving it a try to see how much of an effort it actually is. You may be pleasantly surprised.
EDIT: I haven't tried Handbrake yet, but I've heard very good things about it (I think it got voted best dvd ripper on Lifehacker's Hive Five). I totally forgot until the previous poster mentioned it. It's definitely worth a try.