I am not that familiar with the Raid setup for hard drives but on the over clocking I would be very careful about that this has to do with the processor speed and I think the best way to fix this would be to talk with somebody either locally or possibly the computer's manufacturer tech support at least. They should be able to take it back to normal operation.
For finding out if the software is legal, If you are talking about the Windows operating System you can find that out pretty quick just go thru Windows Update and it will take you thru a verification process and tell you if it is illegal. I have absolute faith in this and it works, If you are legal it will let you through and get all of the updates and also tell you you are legal.
As or backing up the data you can do this with a file transfer program like Windows Explorer or Total Commander or the like. Just copy the files to the external hard drive to a sub directory and they are saved. Or you can use a backup program. Searching Google for backing up your hard drive should be good to give you a lot of info on this subject.
If you want to check for infections use this
I suggest you post a HijackThis log for examination.
A member of the HijackThis Team will walk you through, step by step, how to disinfect your computer.
Once you post your log, don't make any changes to your system, as that could change the results of the posted log, making it difficult to properly clean your system.
Read Preparation Guide for use before posting a HijackThis Log.http://www.bleepingcomputer.com/forums/t/34773/preparation-guide-for-use-before-using-malware-removal-tools-and-requesting-help/
Please read, and follow, all directions carefully!!!
Then, run a log, and post it in the HijackThis forum, at this link below. http://www.bleepingcomputer.com/forums/f/22/virus-trojan-spyware-and-malware-removal-logs/
Do not, fix anything, yet.
A member, of the HJT Team, will help you out.
It may take a while to get a response, because the HJT Team are very busy. Please, be patient, as these people are volunteers. They will help you out, as soon as possible.
Once you have made the post, please, DO NOT make another post in the HJT forum, until it has been responded to by a member of the HJT Team. The first thing they look for, when looking for logs to reply to, is 0 replies. If you make another post, there will be 1 reply. The team member, glancing over the replies, might assume someone is already helping you out, and will not respond. So, just make your post, and let it sit there, until a team member responds. This way you will be taken care of, in the most timely manner.