yeah 3.1 is only 16bit that means it wont even use all of you ram and cpu. it might not even work with the pc133 ram you have. thats also a big difference from the simms they used back then. your best bet, either go 2k pro, which except for its crummy driver database is one if not the best version of windows. of course you guys may hate me for saying this, but a copy of ubuntu linux might also serve your old machine well.
as for 3.1 you wont learn much, it was buggy, slow, and had MANY short commings. the memories still plague me to this day!