Your CPU is just fine. Here is what I think you should change :
1. You might want to go for a slightly newer, higher capacity and faster HDD, not SSD but anything Newer than what you currently have. Even a 250GB SATA II HDD will do just fine. 500GB's are cheaper these days so if you can, just go for that.
2. A bit more Ram will do as Windows 7 Bit can actually take advantage of all 4GB ram you have and more. Bump it up to 6GB or 8GB if you Motherboards allows that. Please note, amount of Ram you will need is dependant on types applications you will be running.
Your PC should ran much quicker after this