well the way I see it....is that this chip (which oddly enough my moms laptop contains the 2400+ XP-M) reaches atleast in the 50's when it's sitting in a laptop. This thing pumps out some hot *** air when my friend plays a game on it (I'm referring to this laptop not my computer in the sig below) so I figure you keep it below 60 mainly preferably below 55 and you should be good. Mines also at 12x200 currently but I have a vcore of 1.85 I just updated my BIOS so perhaps I can turn it down because it's running prime95 with absolutely no problems. I have INSANE cooling though so thats why I have lower temps even though your Vcore is lower than mine.
9 case fans
2 PSU Fans
1 - 80mm Tornado for the CPU
combined with an SLk-900A lapped heatsink and AS5
I would say that the 58C at full load would scare me. You gotta figure it'll be hitting that playing games like doom because your graphics card will also be getting hot and putting that hot air into the mix. What kind of cooling do you have? If you have stock those temps seem about right, but I'd REALLY suggest you get a better heatsink and atleast some AS5 especially for overclocking.
Having the vantec tornado helps too
but is extremely loud. Even with all the fans I have including 2 of them being blower style duct fans, it's the most predominate sound you hear in my case.