You should be able to upgrade to a 940XM. Any newer CPU's will not be compatible with the socket on your motherboard. The GPU is probably your best upgrade option and you should be able to get any mobile card working in there with the right drivers.
Thanks guys. I have the NVIDIA 240 for a GPU, but the i3 processor that I have isn't cutting it. I wanted to make sure I could upgrade to a quad-core processor. Even the older i7 is better. I cant get any info on the board that's in my laptop from the alienware website because I would have been able to tell what I could use just from that. Thanks for all the help. I just cant believe that this system is so slow....even with 4GB RAM. I expected more from an Alienware system