Want Advice re: five hours stop in Singapore airport?

HI,
I am going to Australia at the end of next month with my partner and two children (aged 5 years, and 7 months)
I was just wondering is there much to do in Singapore airport as we have a stop there for five hours.
Should I get some of their currency?
Can you leave the airport and maybe get a taxi into the city - or would it be worth it with the time frame that I have?
I would really appreciate any advice.
Many thanks

Great airport to stop in
theres a free city tour from what i remember available if you have a stopover of 4 hours or more,also cinema,hotels etc
have a look at this article for suggestions
How to pass the time in Singapore airport
http://travel.timesonline.co.uk/article/0,,18409-2388193.html

Probably the best airport in the world to have a stopover in. The tour is good if you want to get out and see something or you can treat yourself to showers, massages, or even get a bed for a few hours.

There's a great roof-top swimming pool at Singapore airport. We had a similiar stop-over and found it great to work down at least 3 hours. Had 2 kids under 3 in tow and they loved it. The hassle of heading around the city on a tour we felt wouldn't be worth it. There is a good website for the airport, check this out before you go.