There are literally hundreds of reasons why a system can run slow. Not enough ram, too much bloatware/ crapware accumulated, viri, etc..... if it is really slow, it is best to re-install windows fresh and have the max ram your system can handle. Slow loading simply means a slow hard drive and a slow cpu- not much you can do about that. Being you have 4g of ram, I'd bet it's too much crapware on the system and/or a viri. run CC cleaner and PC decrapifier. Also run mike lin's startup editor to stop too many programs from auto-loading. Single core systems will see the biggest improvement.