I have a Dell Inspiron 600m with a Pentium 4 Mobile (SSE2 compatible), and running Windows 2000 Pro USP 5.1 with Unofficial Update Rollup (Nov. 30th 2014). In My Experience, I can run most Windows XP only software, but applications that require SSE2 support don't work. I tested Serpent SSE, but I get an error message "The procedure entry point CoGetInterceptorFromTypeInfo could not be located in the dynamic link library ole32.dll". "Could't load XPCOM. I will post a screen shot shortly. I use K-Meleon 76.2 Goanna 20191019, and Newmoon 27.9.6 (20190223) and both work well. Congratulations on your browser builds!