Hello , its been a years since a purchase my pc (lenovo c300 ,windows vista basic). I usually use my laptop(toshiba laptop l745d) for gaming since its faster than my pc(lenovo c300). But after our semester test my laptop suddenly crash every time i open it ,I tried posting it here but the answers are not working 
So i decided to use my pc (lenovo c300) for gaming . My mom upgraded it to windows 7 ultimate and now its more slower on playing MMorpg's. What's the best thing to upgrade on my computer ?

So i decided to use my pc (lenovo c300) for gaming . My mom upgraded it to windows 7 ultimate and now its more slower on playing MMorpg's. What's the best thing to upgrade on my computer ?
My Computer
At a glance
Pre installed windows 8 x64. upgraded to 8.1 ...4g ramAMD Radeon™ HD 6520G
- Computer type
- PC/Desktop
- Computer Manufacturer/Model Number
- Acer Aspire V5-473PG
- OS
- Pre installed windows 8 x64. upgraded to 8.1 via windows store
- Memory
- 4g ram
- Graphics Card(s)
- AMD Radeon™ HD 6520G
- Other Info
- Intel i5-4200u 1.6ghz / NVIDIA geForce GT 740M