Weird speed related issues can be hard to track. Try to think about what you changed on your computer since you had the fast rips? Software or hardware changes? Any new DVD ripping programs? Win2K has sensitive ASPI drivers...they can get whacked out easily. Try searching for "2000 ASPI" in Google.com and you should find an Adaptec file that will update your ASPI layer in Win2K. I can't even rip until my ASPI is installed. Keep in mind that by default, Win2K does not even load an ASPI layer. sux..
Another thing is check the DVD you are trying to rip. Is the problem with every DVD or just one? Could be scratches on the DVD hosing you up.