kabamarutr on 17 January 2014
Since you do not own a high end PC, I recommend Lord of the Rings: Battle for Middle Earth 2. Trust me on this!
Also, the Dawn of War series with any/all expansions (can be found at decent prices).
StarCraft and StarCraft II (if you can manage it)
... and the whole Total War series. Of course there are many more, but these come from the top of my head. If I remember anything else, I'll post it.
Finally, you can check which games you can run on your PC in www.canyourunit.com
This, I stole from grandpa...It's called soap.
