There is no recent security flaw that I'm aware of.  Microsoft did release a bunch of security updates the other day for Windows XP and Internet Explorer that you should consider installing if you haven't already.

Has there ever been any? Thank You

Back a couple of years ago there was some concern.  Click here for a Google search on the topic.

I highly doubt it.  From the articles I reviewed it would appear the flaws effected Server applications.  Secondly, if you were affected, you'd be the first person I've seen in the forums to be affected. 

 

Are you having a particular problem with the system and / or hyperthreading?  In some situations, owners have reported the enabling of hypterthread actually decreased the system performance.  

Thanks for the link. But could you tell me if that would have affected my pc? Thank You

No, i just read an article on this that i never saw before. Thank You for your help.