I recently bought a Dell Inspiron 15R i15RN 5297BK for 300 dollars ( hasn't arived yet). It has an Intel i7 2670QM, 6 gb of ram, 750gb hard drive and a Nividia Geforce gt 525m 1GB gpu. My question is can I do some gaming with this laptop. I usually play games at the lowest resolution with all features turned off. Some of the games im intrested in playing are COD (all of them), Bioshock, Skyrim, battlefield 2 and some others. Also, should I upgrade the ram?
You'll be able to play if you dial down the settings, especially if you lower the resolution, Skyrim is the only demanding title I see on that list and my brother was able to play it at 1650x1050 on low with a fanless 5450, you'll be ok. And that's plenty of RAM, especially for lower-level gaming (graphically of course).
You have enough RAM for regular gaming so you dont need to upgrade it unless your profession involves running real time simulations, rendering etc. 525m might lag quite a bit running Crysis on high but the games you have listed should run fine on medium. It should also handle higher resolutions without lag.
Also, you need to update your video drivers to gain some FPS in skyrim for example.
Here is guide and downloads