Didnt seem to work...crashing still happens

Does it continue to freeze if the Corega USB ethernet adapter is uninstalled from device manager? Have you run memtest to verify it is not a RAM problem? You can run memtest from a knoppix CD.

Yes it still freezes if I remove the Corega ethernet adapter. I can plug the internet cable directly into the back of the tower and the internet will work, but still freeze. I have previously removed the corega adapter from the machine and uninstalled it from device manager and as a result, on device manager, the only thing recognised under network adapters is SiS 900 PCI Fast Ethernet Adapter. I take it this is a different thing to the USB device I removed?

I have tried a RAM test before but didnt really know what to do after testing it. All that happened was a load of white numbers scrolling down a DOS screen.

Here are some things to check before going any further.
1. Does the crash/freeze happen shortly after starting the computer, say within 10 minutes, or does it take longer before it happens? If it happens during or immediately after start-up, then it is most likely a software or driver problem, or a failed component (RAM). If the computer will operate for a while before it freezes, then the problem is often caused by overheating. Check all the fans, especially on the CPU and Video card, to make sure they are working. Also make sure you have good airflow in the case.
2. Will the computer run properly in safe mode? If the computer freezes in normal Windows but will run without problems in Safe Mode for a couple of hours then the problem is usually caused by a problematic driver. Verify your system configuration and check with the component manufacturers website for the correct drivers.
3. Does the problem on occur when you are running a specific application (Internet Explorer) or using a network service? This could be the result of a corruption of Internet Explorer's files, a corrupt network protocol file, a bad network adapter, or corrupt network card driver.
4. Finally the problem could be the result of a Virus or spyware/malware file. Scan the computer with a current anti-virus program and spyware removal software, if you hav not already done so.
Once you check these areas, post back with the results to determine how to proceed.