Hi Mozza, welcome to TSF....
there could be a few reasons why svchost.exe is using up all your resources with the most obvious being some kind of malware so I strongly suggest that you take the time to read through
this thread as it advises on the steps to take before posting a Hijack This log file
here.
Hopefully our security analysts will be able to give you the all clear so we can then concentrate on other possible causes but if they do find an infection of some kind, they will assist you from start to finish to get your system clean.
If you have any questions or problems, please don't hesitate to ask.