try www.doom9.org for guides on dvd ripping and conversions.
u'll probably need
fast processor(over a gig is nice) it still takes around 5 hours to turn a 2 hour dvd into divx on my 1.4ghz.
big hardrive: when you rip a dvd onto your hardrive, the files are around 5 gigs.
win 2k is best(win xp good also): win 98 & me are pure shit when compared to win 2k just for the stablity.
3d card: geforce 3, ati radeon, at least something decent.
dvd drive: faster drive is always better, good brands are reliable. my noname brand drive has been working for me though.
most of this stuff is taken from doom9's newbie guide and my own experience. read it to understand stuff fully.