How do i make my laptop/notebook a wireless modem?

We have a modem at home but it doesn't have built in wifi so we have it connected to a router. We have fast internet (ADSL2 i think) but running through the router, it's very slow. So i was wondering if i could somehow make my laptop a modem? Or a router as well because it would have to be faster than the one we have now. Im running a Acer Aspire 1830 Notebook 32-bit windows 7

Thanks. Oh and please use simple language when replying, i have a general understanding of what you may be talking about but nothing too high tech please