I've read earlier posts describing problems which could be related to yours. It seems to me that a common denominator in these posts could be (a more recent version of) ffdshow. Now, I'm not using ffdshow myselves and I don't know what version you're using. In your case I would however not be using ffdshow. Instead try latest DivX-codec (perhaps also - but not necessary - XviD as well). Shouldn't be a problem for a 1.4GHz Pentium (even if it is the mobile version, though I've no personal experience with that).
Please read my Help2Help-post (and especially item (4) thereof
(and concerning ffdshow (a) under MISCELLANEOUS)).
Please let us know any news.