When I first started using Ubuntu
on a laptop (DELL D600) I would get connex drops too.
If using the default wireless channel
(check the wireless router documentation
to see what the default channel is)
then I would change the channel.
Other things to look at re:connection drops are
1. Interference, and
2. The slim possibility that others
are utilizing your wireless signal. If others are
using your network, the additional "traffic" can
possibly be disconnecting you.
You can tell your router not to broadcast the
SSID - and this way, your wireless network
will be somewhat obscured from other wireless users
who want to use your broadband service for free.
3. This is slightly more 'techie' but you can configure
your wireless router to allow only connections
to machines that it "knows about".
This is done by getting the MAC address from your
laptop, and telling the router to only allow connections
from that particular MAC address.