Whenever the sluggishness is with "online browsing" the problem is almost never RAM.
What browser are you using? How much bandwidth do you have (connection speed you pay for from your ISP)? Are you connecting wirelessly or wired?
One of the biggest factors people don't seem aware of with a laptop/netbook is the amount of software that attempts to update when you finally do get internet connectivity: windows updates, your anti-virus software, google browser, newest firefox browser, ccleaner, flash player, java, outlook, windows live mail, etc can all be trying to grab updates when you connect and it can take most of your bandwidth. Except for your A/V and email I recommend users disable automatic update and take the responsibility to check for these updates themselves periodically.