Repurposing old notebook into wi-fi router

I understand it's probably a dumb question, however quick googling didn't help, so I decided to start a thread. I have an old notebook that I would like to use for OpenVPN, torrents... and wi-fi routing. It's capable of running 24/7 even in hot weather, and will be connected to isp via ethernet. I expect it to provide wireless connection to 4-5 devices at a time.
Can I make it do the job better than cheap wi-fi routers? Do I get it right that I need to buy some fancy expresscard wi-fi adapter...

Repurposing old notebook into wi-fi router