Well to truly find out the solution to your problem, you'll have to be a little bit more specific in your question. By 1.2 processor do you mean 1.2 GHz?. Also, you'll need to find out the amount of RAM (system memory) you have in your laptop. To be honest, I would just avoid gaming on a ''basic'' laptop and go straight to the PC (if you have one) because you can upgrade the RAM and a video card a hell of a lot more easily than in a laptop. I'd suggest a low end video card if you're playing games like medieval war. I used to have an ATI 2600 pro, very good for games like that, and good for games that are more graphically advanced too. Also the 2600 is very cheap for what it delivers. If you're unsure on how to upgrade your RAM or Video card, look for a tutorial on youtube or message me. Hope I helped.
Either a. get a new computer (with more RAM) , b. a new copy of the original medieval, or c. try Shogun Total War. It is older than the original Medieval and covers a conflict rarely scene in RTSs (Feudal Japan). Rome Total War which is still my favorite of the series, despite how big and shiny Empire Total War is, may still run on your computer but it is newer than the original medieval so if your having trouble with that I don't know if Rome would work.