I wouldn't trust PC world as a company to replace and install a toilet roll in my bathroom. They are ok if you know what your looking for but the amount of pish the sales staff can talk is unique in my experience.
The commercial networking department is a joke as well.
All these free scan your computer progs are a con on Nigerian email I need to transfer 1 billion pounds because my church in a third world country is built on a oil reserve and if you send me 5k I will transfer this money to you and you can keep 10% sort of levels.
Guaranteed that all that it will report is that your computer is crap, best solution is to take it to PC world. Pay 100 quid for the resident chimp to dick around with it and loose your data. While another help in the community window licker tries to sell you a new PC, which if you are lucky will just have enough performance to boot the latest microsoft OS but probably not.