Ugh. Your specs don't involve your hard drive and memory. It involves much more.
Your problem is probably that you computer cannot handle it. What most likly happened is that you went from, say, a PIII with a bunch of L2 cache and decent instruction sets, to say, a Celeron (non-d). I use intel because if I mentioned AMD, I know there would be a bunch of people who would have no idea what I Was talking about...
My recomendation: Get your specs (At least from right clicking on my computer and pressing properties) and post em.