It's your internet cache, you can clear it through your browser tool settings or you can download CCleaner which cleans it for you. It's a free program.
Hmmm... 250GB of RAM?? You must have one heck of a motherboard!!
With a DDR3 4GB stick of RAM averaging about $160 per stick, that's a 63 sticks of RAM x $160 = $10,800 worth of RAM.
May I borrow a couple of thousand dollars? Just kidding...

Most netbooks only have 1 or 2 GB of RAM max.
The internet cache will eat up memory rather quick if you don't have a lot of RAM. It should be set to retain no more than 40-50MB. You can do that in the Tools options also. Depends on the browser you're using.
You might try increasing the Page File size also. For you, a 2GB size should be adequate.
If Thrax sees this post, he may have a better idea on recommended Page File size for a netbook.
Also double-check your audio settings and driver. Make sure its up to date.
Go here to read up about the internet cache and how it works and what it does. I hope this helps you!
http://www.clear-cache-cleaner.com/