Is there a way I can redesign my current computer?

I'm 15 years old, and I have an IBM T43. My uncle gave if to me since my last computer broke down. So far it's been really good but I've been starting find some stuff wrong with the hardware. The plate that surrounds the keyboard is coming off, the battery cover has a big hole in it, the bottom left mouse broke off. And sometimes, the tap mouse freezes so I bought a separate USB mouse. And all-in-all, the computer just looks old and dirty. Is there a way I can take it to a factory and replace all the hardware in to something I'd like? Maybe HP looking? And change the whole thing dramatically? (Also I'd like to add Windows 7, and a new graphics card)