I just noticed you had another thread as well. Hence the new fan in your system. Have you checked the temperature of the video card when the beeping occurs? In fact, have you checked the temperatures for everything before and after the beeping occurs?
I noticed in your other thread you checked the temperatures in the BIOS. The BIOS doesn't always give the correct temperatures. It's also incapable of showing your temperatures when under load.
Here are a few programs you can use to check and monitor your temperatures: Core Temp Real Temp - CPU temperature monitoring Download SpeedFan - Access temperature sensor in your computer
Some of the above do not work with Single Core CPU's, but it doesn't hurt to try.
That being said, I would definitely monitor your temperatures directly while using the system. If you need to check the temperature of your graphics card, the above programs provide that option as well with the exception of Core Temp if I remember correctly. Taking your previous thread into account here, I'd say you're still overheating. But there isn't any reason the website itself would be causing it, at least not through your graphics card. It's simply text with a few image files. If anything the site would cause your CPU usage to spike.