Help - I think Ive been virused

Heres a strange one - xp auto updates no longer work - mse updates wont work - cant get to any microsoft websites. mse security essentials is always on and says its cleaning up and Im protected - Im also running regular scans. But something stinks here. wuauserv and bits are missing from services also.
So I just grabbed malwarebytes from on of our trusted uploaders - but before I run it - How do I know what is attached to one of my patched exes or cracks (especially reg keys and system 32) and what is an infection. my xp is genuine and so are many of my apps - but a lot are not
In the past I used to fix this kinda crap by just formatting and reinstalling - but I am so over rebuilding every other month.
Any advice here would be really appreciated. Cheers.


Old age and treachery beats youth and good looks everytime

Thanks - I should have checked this......