I had a feeling you might be using singtel the moment i read the
first post. As LatecomerX asked, is the problem coming from the
wireless router or the actual Singtel connection itself?
If other computers on your wireless network get disconnected
frequently as well, there's 2 things you need to check.
Are all the phones sharing the same line connected to
microfilters (the little phone line sockets that came along with
your modem package)? If I'm not wrong, if someone else in the house
uses the phone while you're on the internet, you could get problems
with your connection. If need be, you might wanna go down to a
computer shop to get yourself a few of them.
When you use the phone normally, is the line noisy? If this is
true, good luck! It's something I used to hear alot from my friends
who use Singtel. They'd be happy to be able to remain connected for
even 5 minutes at a stretch. If this is the case, you can try
calling Singtel to inform them of the situation. And they will
TRY to solve the line problem for you. 'Try' being
the keyword here, cos it's not an easily resolved situation. The
problem could lie anywhere from one of Singtel's base stations to
even the phone wiring in your house. But I believe one of my
friends managed to resolve the situation by connecting the modem to
a phone jack that was located nearer to the main door (because the
wiring to his room was slightly faulty).
Hope this helps you! 
