Verified answer

you should have 512 but only 508 is opened best thing to do is go buy another stick of memory so you have more there it is asking for for faster play. also there is nothing yu can deleteto give you more ram

If you're in the Us, you can buy RAM at stores like Best Buy and Circuit City. they can install it for you if you bring the computer in. (Just the main case, not the monitor, keyboard, etc.) Depending on the type your computer needs, 1GB can run from around $30 to $75 or so. You might just want to install another 512MB - that would be cheaper and give you a usable 900MB or so.

The best option is to buy more RAM, not only will the game run better but your comp will.

But a not so efficient thing to do is to go to Ctrl + Alt + Del -> Processes (tab), then end any processes that you are not using. DO NOT end any processes that are "system" only end "user" processes, remember not all user processes can be ended so only end ones that you know you are not using....

Again, buying more RAM is the best option and your not only upgrading the game you are upgrading your whole computer!