I7 temps problem/question

Hello,

I'm new to building my own pc so I'm pretty much a noob about the things. I have built my very first rig about half a week and I was very excited when it ran without any errors. Now I'm considering overclocking but I don't know if my temps are just too high. Anyway here are the system specs and temps:

-specs-

Mobo:Gigabyte EX-58 UD5
Cpu:i7 920 D0 stepping @2.8 (w/ intel turbo=21.0 x multiplier)
Heatsink: TRUE 1366 rt (without any adittional fans, using the 1600 rpm Tr fan that came with it)(not lapped)
TIM:AC MX-2 (applied using the line method)
GPU:HD 4890
PSU: Silverstone OP800 (800W)
Ram:Corsair triple channel 6GB 1600mHz cl9
Case: CM690 with 3 stock fans 2 zalman 75cfm fans(still waiting for extra fans)

-temps-

The ambient is about 22-25

idle:
according to speedfan 4.39 and easy tune 6 the cpu temp (tcase) is 28-29C and the core temps(tjunction) are 23 to 27 C(core temps lower than tcase???)

ok here's the problem according to real temp 3.00 the core temps are 38 to 42C!!!!! (isnt't that too high for idle?also such difference between speedfan and real temp is really strange I heard that the real temp was more reliable but if tcase is really 28-29C, isn't 13C difference between tcase and tjunction too much?)

load(after running prime 95 small fft for half an hour) :
speedfan and easy tune: 42C tcase and 48-51C tjunction
real temp:62-66 tjunction

So which tjunction reading is the right one? Are these temps too high? If it's too high what should I do: remount the heatsink, lap it, do a pressure mod on it,get additional fans or simply get a new heatsink? Can I overclock using this setup?

Thank you

Thank you for the reply. Now that I know I'm doing fine I guess it's time to go for overclocking