First,i assume that your connection is:
CyberWorld -> Singnet Modem -> PC
think of the router as a satellite "broadcasting" the
internet around the house
If your laptop is placed a distance away from the PC and modem,i
suggest you go wireless.
Depending on your wireless card,there may be some percentage of
speed loss.Only Intel Centrino technology(according to my testing)
has little and minor loss.
CyberWorld -> Singnet Modem -> Router -> PC
You must connect the router between the modem and the PC.
Ethernet cable from modem to PC originaly now to router first
then PC.
My example of router used in this case is Linksys WRT54G,there's
4 ethernet slot for you to connect ethernet cable up to 4 PC.
The CD that come with the router should configure everything in
one go.
Finally,dont forget to secure your wireless signal to prevent
mooching,that is - people using your network for free to surf
internet.
PS:Im not sure if there will be complication in this guide due
to ADSL technology since im using Starhub Maxonlin,which connect
via Cable.