CPUz will also tell you whats installed on your computer. It's usually difficult to get any kind of decent (desktop comparable) FPS rates out of a laptop. Find out what your laptop's maximum supported RAM is, and upgrade to that. Also, DDR400 might actually be cheaper than DDR333 and will be backwards compatible. Aside from that, I've had exceptionally poor luck with PNY anything.. so I'd stay away from them. G.Skill has always performed well and lasted a long time for me. You may also consider investing in a laptop cooler - usually like a pad with fans in it that your laptop sits on. You can also try elevating the back of the laptop a little bit - HP laptops commonly have fan exhaust on the bottom of the laptop, which is useless for any kind of cooling, especially on a soft or uneven surface. PK was right that heat is a common murderer of laptop performance.
Sorry for the run-on post, let us know how it turns out.