You can download and run the utility below to determine if your Pentium IV processor does support SSE3.

Please go to:

http://www.cpuid.org

Download the CPU-Z utility and it will show what is supported by your processor.

When you launch CPU-Z, on the first screen there is a field that is labeled “Instructions”.  Next to “Instructions” will list what is supported by your processor.  If supported it will say “SSE (1, 2, 3)”  If you see a 3 in paranthesis that indicates your processor does support SSE3.