windows doesn't like being shut down too hard.
there's actually quite many things can go wrong with windows;
if you were running lubuntu from within windows (iirc that's what wubi does) i'm not surprised you were having problems.
if you're hardware is healthy, with these specs you should be running lubuntu just fine, no need to upgrade any hardware!
i've been running lubuntu with 512mb ram and a 1.3GHz processor,no problem.
i recommend to:
first: install windows on the first partition of the first hd (if you feel you need it).
second: install lubuntu in the free space. i don't know about linux and swap, but i never ever saw any kind of linux using more than 10% rams worth of swap space. in my opinion, 1gig of swap is plenty in your case.