After looking at the User Manual for your Laptop, it states it will support up to 8 GB of total RAM in two SODIMM slots. So that's up to two 4 GB sticks.
Here's a screen capture of the page in the manual I'm referring to:
You'll be able to install the 64-bit version of Windows 7 and you can run 4GB of RAM and you'll be rocking. Just be sure that they're a "matched set" so that there is no issues between different manufacturers, etc.
I highly recommend using Mushkin RAM, stable and rock solid. Plus it's an American company based in Denver, CO. I have never had a bad stick from Mushkin.
Here's a matched set from Newegg for $49.99 with free shipping!
Mushkin Enhanced Essentials 4GB (2 x 2GB) 200-Pin DDR2 SO-DIMM DDR2 800 (PC2 6400) Dual Channel Kit Laptop Memory Model 996577