500Mhz addition for your processor speed will not make a huge boost to your processor performance..barely noticeable for your daily application..it just 14% gain from the stock clock..
try to push it until 4.5 to reach a "new world"..:D
mmm, i don't get the point that you said not big change in reading program like Speedfan and cpuid..
as far as i know, cpuz (http://www.cpuid.com/softwares/cpu-z.html)
is the standart tool to observer your cpu configuration..including your core clock speed..
AIDA from lavalyst is another good software..