Mac mini stopped 'seeing' airport express

Question

Yesterday my mac mini stopped being able to sustain a connection to my wireless network (cable modem connected to Airport Express base station). All the other computers on the network are still working fine; the mini will connect for a bit (at weaker strength than it used to) and after a short time - could be seconds, could be 5 or so minutes - disconnects. Once the mini has lost connectivity it cannot even 'see' the presence of the airport express. All the other computers in the house (both dells) still connect just fine. I'm therefore assuming that the problem lies in the mini's airport card (specs listed in my profile, and yes, the System Profiler still does 'see' the card).
Just to be thorough, I've tried the following:
1) plugging the cable modem directly into the mini works - but then, of course, no one else gets internet access.
2) resetting everything - cable modem, airport express, network settings on mini - followed by a restart does not help the computer stay connected. Maybe I get 5 minutes as opposed to one.
So here're my questions:
1) Is it possible to have the airport card replaced in a mini?
2) Would it be a better option (financially, aggravation, likelihood of recurrence) to get an airport extreme base station instead? Then I could hardwire the mini to the network and use wireless for the other computers (is that correct?).
3) Is there something here I'm overlooking that I should consider?
THANKS so much!
frano

Answer 1

1) Is it possible to have the airport card replaced in a mini?
Yes. It's a discrete component that can be removed and replaced if faulty, as can the antenna which is also a possible culprit. Just as possible too is that the antenna is not firmly connected, which can also be remedied by servicing.
2) Would it be a better option (financially, aggravation, likelihood of recurrence) to get an airport extreme base station instead? Then I could hardwire the mini to the network and use wireless for the other computers (is that correct?).
It would always be a better proposition to hardwire a system to a network rather than use wifi - not only for reliable connectivity but also for throughput. I'm not sure that I would consider an airport base station however, since there are a number of other wifi routers available at typically lower cost and which are every bit as compatible if you were to decide to go that route. I use a Belkin at home, which at $40 is inexpensive, yet provides a more reliable signal than my airport extreme base station did.
3) Is there something here I'm overlooking that I should consider?
Interference. While it's easy to assume that there must be a problem with the mini since your other computers don't have the same problem, that isn't the only conclusion. The mini's great weakness in wifi use is that the antenna is partially screened by the system's casing and as a result, in the most ideal of circumstances it will typically give lower signal strength and poorer signal quality than you'd get with almost any other system. That isn't a problem in most situations, but it does mean that if there is a reduction of signal transmitted (and the Airport Express is pretty low level transmission power even in normal wifi terms) or a source of interference in the area, the mini's wifi connectivity will suffer more readily and notably than almost anything else.
You can look for indications of this sort of issue with a good analytical utility such as AP Grapher (http://www.chimoosoft.com/apgrapher.html) which can show you not just the simple matter of signal strength, but also what other factors may be playing a part, such as noise. That might give some additional clues.