Just look at the 6th post in this thread (The one by Terminaor). I think you have to log in to view the link though. (This is the most I can help you on my phone)
Edit: Got the link if you don't want to log in.
http://www.systemrequirementslab.com/cyri/requirements/call-of-duty-world-at-war/10803/?p=r
This site gives minimum requirements. Building a PC is recommended just because price wise you'll get so much out more than if you get a laptop, but you lose out on the mobility if that's something that's important to you. The best test is to just download WaW and try to run it on your laptop already.