Want to tune up my S40, need help.

[siggi]

Hello, I just got a Volvo S40 1.8 1997, it got 113000 km on it and is a very nice car and I like it alot, but I want to tune it up a little bit and I was wondering what I can do with it.
How much trouble is it to put a turbo on the 1.8 engine ? is it easyer to swap the engines ? what should I think about changing in it now ? I am going to change the fuel filter later this week and I am geting a new time belt later this month, what else is it that I need to change ? i'm not sure that the car have got a lot of work done on it the last 30 000 km so I want to change every thing that needs to be changed.