no, it isn't common, but we need more information.

what brand/model wireless base station? 802.11b, g or n?
are you using any encryption? wep? wpa?
is it using dhcp for configuration when connecting to the base station?
how far away is the macbook from the base station?
how many other devices are connected to the base station?
any possible source of interference such as a microwave oven or 2.4 ghz cordless phone (even from a neighbor) ?
does it work with someone elses base station (ideally a different make)?
also, what version of osx ? 10.4.9 has some airport updates which may be related.

one thing to try is if you are using any encryption, turn it off for test purposes and see if it makes a difference. and, if it is flaky with another base station (i.e. at starbucks), then maybe apple needs to take a look at it.